MyBatis筆記(二)————PersistenceException產生與解決 和 MyBatis的高階使用(主鍵回填)
阿新 • • 發佈：2018-12-26
(MySQL+Eclipse)
①
十二月 11, 2018 5:02:00 下午 org.apache.catalina.core.StandardWrapperValve invoke 嚴重: Servlet.service() for servlet [empServlet] in context with path [/MyBatisQ] threw exception org.apache.ibatis.exceptions.PersistenceException: ### Error updating database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLTransactionRollbackException: Lock wait timeout exceeded; try restarting transaction ### The error may involve qiu.mapper.EmpDAO.delEmp-Inline ### The error occurred while setting parameters ### SQL: delete from emp where empid=?; ### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLTransactionRollbackException: Lock wait timeout exceeded; try restarting transaction at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30) at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:200) at org.apache.ibatis.session.defaults.DefaultSqlSession.delete(DefaultSqlSession.java:213) at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:67) at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:59) at com.sun.proxy.$Proxy49.delEmp(Unknown Source) at qiu.servlet.EmpServlet.doPost(EmpServlet.java:81) at qiu.servlet.EmpServlet.doGet(EmpServlet.java:35) at javax.servlet.http.HttpServlet.service(HttpServlet.java:620) at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at qiu.base.EncodingFilter.doFilter(EncodingFilter.java:28) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:315) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLTransactionRollbackException: Lock wait timeout exceeded; try restarting transaction at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) at java.lang.reflect.Constructor.newInstance(Unknown Source) at com.mysql.jdbc.Util.handleNewInstance(Util.java:425) at com.mysql.jdbc.Util.getInstance(Util.java:408) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:951) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3973) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3909) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2527) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2680) at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2490) at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1858) at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:1197) at sun.reflect.GeneratedMethodAccessor59.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.apache.ibatis.logging.jdbc.PreparedStatementLogger.invoke(PreparedStatementLogger.java:59) at com.sun.proxy.$Proxy38.execute(Unknown Source) at org.apache.ibatis.executor.statement.PreparedStatementHandler.update(PreparedStatementHandler.java:46) at org.apache.ibatis.executor.statement.RoutingStatementHandler.update(RoutingStatementHandler.java:74) at org.apache.ibatis.executor.SimpleExecutor.doUpdate(SimpleExecutor.java:50) at org.apache.ibatis.executor.BaseExecutor.update(BaseExecutor.java:117) at org.apache.ibatis.executor.CachingExecutor.update(CachingExecutor.java:76) at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:198) ... 30 more
只是超時了,重啟Tomcat或編譯工具(MyEclipse、Eclipse。。。),分享些我搜到的文章：http://blog.itpub.net/29654823/viewspace-2150471/、https://blog.csdn.net/zc474235918/article/details/72731363/、https://www.cnblogs.com/simpledev/p/5426705.html
②
MyBatis的主鍵回填：
1、在插入資料時，如果主鍵欄位為自動增長的欄位，插入資料後想要知道主鍵值是多少，MyBatis提供了主鍵回填的功能。
2、要使用主鍵回填的功能，MyBatis的配置檔案mybatis.xml中<setting name=“useGeneratedKeys” value=“true”/>的value必須為true或者在XXXDAO.xml中有selectKey子元素的insert元素中加屬性useGeneratedKeys=“true”(來獲取有資料庫內部生成的主鍵)
3、對映檔案（XxxDAO.xml）中必須增加<selectKey>標籤，其標籤的keyColumn屬性：資料庫表的欄位名、 keyProperty屬性：Javabean的變數名（該值要與keyColumn值對應）、resultType屬性：select查詢的值的返回型別、order屬性（預設值為BEFORE）：回填順序，在插入語句執行前或者在插入語句執行後獲取主鍵值（可選BEFORE或AFTER）注：[①一般SQLServer和MySQL的選AFTER，Oracle的選BEFORE ②主鍵能自動遞增選擇AFTER，主鍵不能自動遞增則選擇BEFORE]
（1）
【empId是自動遞增的主鍵欄位，且在mybatis配置檔案中加上“主鍵回填為true”的程式碼】
————mybatisQ.xml
<?xml version="1.0" encoding="UTF-8"?>
<!-- mybatis核心配置檔案的dtd -->
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<!-- 引用jdbc配置檔案 -->
<properties resource="jdbc.properties"/>
<settings>
<setting name="cacheEnabled" value="true" /><!--二級快取-->
<setting name="useColumnLabel" value="true" />
<setting name="useGeneratedKeys" value="true" /><!--主鍵回填-->
<setting name="mapUnderscoreToCamelCase" value="true" />
<setting name="logImpl" value="STDOUT_LOGGING" /><!-- 列印SQL語句 -->
</settings>
<!-- 使用package為整個包中所有的Javabean指定別名，使用typeAlias為一個類指定別名，這兩個引數只能二選一 -->
<typeAliases>
<!-- 配置JAVABEAN的短名稱，使用時，首字母(其實別名都)不區分大小寫
alias=別名
type=類的全路徑（包含了包名）
-->
<typeAlias alias="EmpVo" type="qiu.vo.EmpVo"></typeAlias>
<typeAlias alias="EAccVo" type="qiu.vo.Emp_AccountVo"></typeAlias>
</typeAliases>
<!--環境配置，配置的是開發者模式(development),工作模式（work） -->
<environments default="development">
<environment id="development">
<!-- 宣告jdbc事務處理，type=[JDBC、MANAGED] -->
<transactionManager type="JDBC"></transactionManager>
<!-- 資料來源：資料庫連線池 ，type=[UNPOOLED、POOLED、]-->
<dataSource type="POOLED">
<!-- 從這裡看出,jdbc.properties裡的引數名,可以自定義,
最好帶個類似"jdbc."這樣的字首,這樣不會和其他的properties的引數名弄混
-->
<property name="driver" value="${jdbc.driverClassName}"/>
<property name="url" value="${jdbc.driverUrl}"/>
<property name="username" value="${jdbc.user}"/>
<property name="password" value="${jdbc.password}"/>
</dataSource>
</environment>
</environments>
<!-- mappers可以一個一指定，也可以通過包一次性指定（二選一） -->
<!-- 引用Mapper介面的sql對映檔案 -->
<mappers>
<package name="qiu/mapper"></package>
</mappers>
</configuration>
————DBConnQ.class
public class DBConnQ {
static SqlSession session=null;
public static SqlSession getSession(){
try {
InputStream configuration=Resources.getResourceAsStream("mybatisQ.xml");
SqlSessionFactory sessionFactory= new SqlSessionFactoryBuilder().build(configuration);
session=sessionFactory.openSession();
} catch (Exception e) {
e.printStackTrace();
}
return session;
}
}
————EmpDAO.xml
<insert id="addEmp" parameterType="qiu.vo.EmpVo" >
<!--empId是自動遞增的主鍵欄位-->
<selectKey keyColumn="empId" keyProperty="empId" resultType="int" order="AFTER">
SELECT LAST_INSERT_ID()
</selectKey>
<![CDATA[
insert into emp(empName,password,age,sex,depId,job,status,remark) values(#{empName},#{password},#{age},#{sex},#{depId},#{job},#{status},#{remark});
]]>
</insert>
————EmpDAO.class
void addEmp(EmpVo empvo);
————Emp_AccountDAO.xml
<insert id="addEacc" parameterType="qiu.vo.Emp_AccountVo" >
<![CDATA[
insert into Emp_Account(empId,bankName,bankaccount) values(#{empId},#{bankName},#{bankAccount});
]]>
</insert>
————Emp_AccountDAO.class
void addEacc(Emp_AccountVo eaccvo);
—————將add頁面的form傳來的值接收（我使用Servlet）
@ WebServlet(name = "empServlet", urlPatterns = { "/empServlet" })
public class EmpServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request,response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
SqlSession sqlSession=DBConnQ.getSession();
EmpDAO empBase=sqlSession.getMapper(EmpDAO.class);
EmpVo empVo=new EmpVo();
Emp_AccountVo empaccVo=new Emp_AccountVo();
Emp_AccountDAO eaccBase=sqlSession.getMapper(Emp_AccountDAO.class);
//localhost:8080/MyBatisQ/empServlet?action=add
String action=request.getParameter("action");
if(action.equals("add")){
String empName=request.getParameter("empName");
String password=request.getParameter("password");
int age=Integer.parseInt(request.getParameter("age"));
String sex=request.getParameter("sex");
int depId=Integer.parseInt(request.getParameter("depId"));
String remark=request.getParameter("remark");
String bankName=request.getParameter("bankName");
String bankaccount=request.getParameter("bankaccount");
String job=request.getParameter("job");
//先將兩表的值都放在MappedStatement中,再一起commit(也可以先emp表commit再Emp_Account表commit,不過要比較下速度或效能)
empVo.setEmpName(empName);
empVo.setPassword(password);
empVo.setAge(age);
empVo.setSex(sex);
empVo.setDepId(depId);
empVo.setStatus(1);//預設為在職
empVo.setRemark(remark);
empVo.setJob(job);
empBase.addEmp(empVo);//要先主鍵回填,才可以有empId,因為還沒有載入到資料庫表中
empaccVo.setEmpId(empVo.getEmpId());
empaccVo.setBankName(bankName);
empaccVo.setBankAccount(bankaccount);
eaccBase.addEacc(empaccVo);
sqlSession.commit();
//以下轉向EmpList列表頁面(無需提供對應程式碼)
List<EmpVo> eList=empBase.listemp();
request.setAttribute("empList", eList);
request.getRequestDispatcher("EmpList.jsp").forward(request, response);
}
}推薦看看（他人好文，註釋裡的MapperStatement就是在裡面看到的）——【原理分析之二：框架整體設計、《深入理解mybatis原理》 MyBatis的架構設計以及例項分析——二、MyBatis的主要構件及其相互關係】
Emp表和Emp_Account表的相同欄位為empId。以下為“新增介面”（含Emp_Account表對應控制元件；若值傳至後臺，兩表都要有對應變化，正如上面那兩張“empId都為1”資料庫表圖）:
所以要實現“添加了Emp表記錄的同時也新增Emp_Account表記錄”，就要使用主鍵回填，將未commit於資料庫表的主鍵值賦於empVo的empId屬性，那麼
這條語句的getEmpId（）有對應的主鍵值；若無主鍵回填，還使用這條語句，就會報NullPointerException——500異常。
（2）
自定義回填：
【主鍵empId欄位不能自動遞增，且在 XxxDAO配置檔案中加上“主鍵回填為true”的屬性】這樣就能夠通過編寫這個查詢語句，來自定義主鍵的生成規則(如：從1開始每次取最大值加1)。在插入時，需要將主鍵一起插入，因為這時DBMS並沒有自動生成主鍵，而是手動生成的。(將其order屬性設為BEFORE後，就可以在真正執行插入前執行一次查詢，並將結果填寫到要插入的主鍵上。)
<!--開啟自定義生成主鍵,指明主鍵的那一列是名為id的列-->
<insert id="addBook" parameterType="book" useGeneratedKeys="true" keyProperty="id">
<!--查詢結果給empId屬性,查詢結果是int型別,查詢發生在真正執行插入之前-->
<selectKey keyProperty="empId" resultType="int" order="BEFORE">
SELECT IF(MAX(empId) is NULL,1,MAX(empId)+1) FROM emp
</selectKey>
INSERT INTO emp(empId,empName,age, sex) VALUES (#{empId},#{empName}, #{age},#{sex})
</insert>前提：empId是主鍵但不是"自動遞增"，並且我的全部程式碼與（1）中程式碼呈現一模一樣。導致報錯：【在MyBatis筆記(一)————PersistenceException產生與解決(考考你CRUD基礎扎不紮實~)——③中也寫有這個異常】
十二月 18, 2018 11:06:11 上午 org.apache.catalina.core.StandardWrapperValve invoke
嚴重: Servlet.service() for servlet [empServlet] in context with path [/MyBatisQ] threw exception
org.apache.ibatis.exceptions.PersistenceException:
### Error updating database. Cause: java.sql.SQLException: Field 'empId' doesn't have a default value
### The error may involve qiu.mapper.EmpDAO.addEmp2-Inline
### The error occurred while setting parameters
### SQL: insert into emp(empName,password,age,sex,depId,job,status,remark) values(?,?,?,?,?,?,?,?);
### Cause: java.sql.SQLException: Field 'empId' doesn't have a default value
at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:200)
at org.apache.ibatis.session.defaults.DefaultSqlSession.insert(DefaultSqlSession.java:185)
at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:57)
at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:59)
at com.sun.proxy.$Proxy4.addEmp2(Unknown Source)
at qiu.servlet.EmpServlet.doPost(EmpServlet.java:96)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at qiu.base.EncodingFilter.doFilter(EncodingFilter.java:28)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:313)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.sql.SQLException: Field 'empId' doesn't have a default value
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:964)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3973)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3909)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2527)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2680)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2490)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1858)
at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:1197)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.ibatis.logging.jdbc.PreparedStatementLogger.invoke(PreparedStatementLogger.java:59)
at com.sun.proxy.$Proxy9.execute(Unknown Source)
at org.apache.ibatis.executor.statement.PreparedStatementHandler.update(PreparedStatementHandler.java:46)
at org.apache.ibatis.executor.statement.RoutingStatementHandler.update(RoutingStatementHandler.java:74)
at org.apache.ibatis.executor.SimpleExecutor.doUpdate(SimpleExecutor.java:50)
at org.apache.ibatis.executor.BaseExecutor.update(BaseExecutor.java:117)
at org.apache.ibatis.executor.CachingExecutor.update(CachingExecutor.java:76)
at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:198)
... 29 more所以解決（一步一步來 ）：
將XxxDAO配置檔案中"id為addEmp"的insert元素裡的程式碼替換掉，
改成
還是會報錯:
( 前提：empId主鍵不能自動遞增。報錯原因：
一：insert語句中沒有empId欄位，導致報上面的異常 “Field 'empId' doesn't have a default value”
改為：
二：不能在插入執行後 回填主鍵值,因為會報下面的異常“Column 'empId' cannot be null”
改為：
按道理，做到這裡，是解決完了問題，
由於我將“add”與“update”合併在一起，而且
將empVo(含有主鍵回填的empId)傳給方法,導致結果還是錯誤的或者出現了不想要的 “ 結果 ” ：
---------------------***********給出對應程式碼************---------------------
————EmpVo
public class EmpVo implements Serializable{
//可使用Integer包裝類的型別,不需要區分大小寫,但是必須與"資料表的欄位對應單詞",不可或多或少或寫錯
private Integer empId;
private String empName;
private String password;
private int age;
private String sex;
private int status;
private int depId;
private String job;
private String remark;
public Integer getEmpId() {
return empId;
}
public void setEmpId(Integer empId) {
this.empId = empId;
}
public String getEmpName() {
return empName;
}
public void setEmpName(String empName) {
this.empName = empName;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public int getStatus() {
return status;
}
public void setStatus(int status) {
this.status = status;
}
public int getDepId() {
return depId;
}
public void setDepId(int depId) {
this.depId = depId;
}
public String getRemark() {
return remark;
}
public void setRemark(String remark) {
this.remark = remark;
}
public String getJob() {
return job;
}
public void setJob(String job) {
this.job = job;
}
@Override
public String toString() {
String msg="empId="+empId+",empName="+empName+",password="+password+",age="+age+",sex="+sex+",status="+status+",depId="+depId+",job="+job+",remark="+remark;
return msg;
}
}
————EmpVo4
public class EmpVo4 implements Serializable{
//可使用Integer包裝類的型別,不需要區分大小寫,但是必須與"資料表的欄位對應單詞",不可或多或少或寫錯
private Integer empId;
private String empName;
private String password;
private int age;
private String sex;
private int status;
private String statusRemark;
private int depId;
private String depName;
private String job;
private String remark;
private Emp_AccountVo eAcc;
private Emp_TaskVo eTask;//一對一情況下用association標籤,在配置檔案中
public String getStatusRemark() {
return statusRemark;
}
public void setStatusRemark(String statusRemark) {
this.statusRemark = statusRemark;
}
public String getDepName() {
return depName;
}
public void setDepName(String depName) {
this.depName = depName;
}
public Emp_AccountVo geteAcc() {
return eAcc;
}
public void seteAcc(Emp_AccountVo eAcc) {
this.eAcc = eAcc;
}
public Emp_TaskVo geteTask() {
return eTask;
}
public void seteTask(Emp_TaskVo eTask) {
this.eTask = eTask;
}
public Integer getEmpId() {
return empId;
}
public void setEmpId(Integer empId) {
this.empId = empId;
}
public String getEmpName() {
return empName;
}
public void setEmpName(String empName) {
this.empName = empName;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public int getStatus() {
return status;
}
public void setStatus(int status) {
this.status = status;
}
public int getDepId() {
return depId;
}
public void setDepId(int depId) {
this.depId = depId;
}
public String getJob() {
return job;
}
public void setJob(String job) {
this.job = job;
}
public String getRemark() {
return remark;
}
public void setRemark(String remark) {
this.remark = remark;
}
@Override
public String toString() {
String msg="empId="+empId+",empName="+empName+",password="+password+",age="+age+",sex="+sex+",status="+status+"(statusRemark="+statusRemark+"),depId="+depId+"(depName="+depName+"),job="+job+",remark="+remark+",taskName="+eTask.getTaskName()+",taskRemark="+eTask.getTaskRemark()+",bankName="+eAcc.getBankName()+",bankAccount="+eAcc.getBankAccount();
return msg;
}
}
————EmpDAO
List<EmpVo> listemp();//介面,要定義方法,而不是變數,也不能static final,只能public和abstract
List<EmpVo4> listEmp_EAcc_ETask_EDep_EStatus();
List<EmpVo4> listEmp_EAcc_ETask_EDep_EStatus_If(EmpVo empvo);
————EmpDAO配置檔案
<resultMap type="qiu.vo.EmpVo4" id="allSelect">
<id column="empId" property="empId"/>
<result column="empName" property="empName"/>
<result column="password" property="password"/>
<result column="age" property="age"/>
<result column="sex" property="sex"/>
<result column="status" property="status"/>
<result column="statusRemark" property="statusRemark"/>
<result column="depId" property="depId"/>
<result column="depName" property="depName"/>
<result column="job" property="job"/>
<result column="remark" property="remark"/>
<association property="eTask" javaType="ETaskVo">
<id column="empId" property="empId" />
<result column="taskName" property="taskName"/>
<result column="taskRemark" property="taskRemark"/>
</association>
<association property="eAcc" javaType="EAccVo">
<id column="empId" property="empId" />
<result column="bankName" property="bankName"/>
<result column="bankAccount" property="bankAccount"/>
</association>
</resultMap>
<!--select標籤都對應介面中的一個方法，
id屬性：指定介面中具體的方法名 , 其值必須唯一
resultType：執行sql返回的結果型別,有時候也就是指定介面中對應方法的List的尖括號裡的Javabean
xml的檔名稱必須與介面名稱相同,並且必須在同一個包中
-->
<select id="listemp" resultType="qiu.vo.EmpVo">
<!--
格式化sql語句的標籤；
當"裡面的SQL語句裡含有特殊字元,如'小於號''大於號'",就能起到作用,處理"讀取時"異常;
即，處理>,<等特殊符號時必須加上CDATA標記。
-->
<![CDATA[
select * from Emp;
]]>
</select>
<select id="listEmp_EAcc_ETask_EDep_EStatus" resultMap="allSelect">
<!--
如果association或collection 關聯物件對應的表中有欄位與主表字段同名，則必須通過欄位別名的方式區分開來，
MyBatis最終是把別名對映到物件的屬性上。如departmentDetail中的depid列使用別名detail_id
那是不是不給別名他就null???
-->
<![CDATA[
select e.*,d.depName,s.statusRemark,k.taskName,k.taskRemark,a.bankName,a.bankaccount from emp e
inner join emp_dep d on d.depId=e.depId
inner join emp_status s on s.statusId=e.status
left join emp_task k on k.empId=e.empId
left join emp_account a on a.empId=e.empId
]]>
</select>
<!--
EmpVo型別傳進來,沒關係,反正只是為了做if判斷,改為empVo4型別,一樣的,因為一樣的變數,只不過empVo4多了Javabean物件
-->
<select id="listEmp_EAcc_ETask_EDep_EStatus_If" resultMap="allSelect">
<![CDATA[
select e.*,d.depName,s.statusRemark,k.taskName,k.taskRemark,a.bankName,a.bankaccount from emp e
inner join emp_dep d on d.depId=e.depId
inner join emp_status s on s.statusId=e.status
left join emp_task k on k.empId=e.empId
left join emp_account a on a.empId=e.empId
]]>
<where>
<if test="empName!=null and empName!='' ">
and empName like concat('%',#{empName},'%')
</if>
<if test="status>-1 ">
and status=#{status}
</if>
<if test="depId>0">
and e.depId=#{depId}
</if>
<if test="sex!=null and sex!='' ">
and sex=#{sex}
</if>
<if test="age>0 ">
and age=#{age}
</if>
</where>
</select>
————EmpServlet
if(action.equals("add")){
String id=request.getParameter("empId");
String eage=request.getParameter("age");
int age=0;
int empId=0;
if(id==null && !id.equals("")){
empId=Integer.parseInt(id);
}
//int型別的欄位對應的輸入框要是沒有填值,都會報錯"java.lang.NumberFormatException: null"
if(!eage.equals("")){
age=Integer.parseInt(eage);
}
String empName=request.getParameter("empName");
String password=request.getParameter("password");
int depId=Integer.parseInt(request.getParameter("depId"));//下拉框一定賦值,零或者其他值
String sex=request.getParameter("sex");
// int status=Integer.parseInt(request.getParameter("status"));
String remark=request.getParameter("remark");
String bankName=request.getParameter("bankName");
String bankaccount=request.getParameter("bankaccount");
String job=request.getParameter("job");
empVo.setEmpName(empName);
empVo.setPassword(password);
empVo.setAge(age);
empVo.setSex(sex);
empVo.setDepId(depId);
empVo.setStatus(1);//預設為在職
empVo.setRemark(remark);
empVo.setJob(job);
empaccVo.setBankName(bankName);
empaccVo.setBankAccount(bankaccount);
if(empId>0){
empBase.undateEmpAll_SetIf(empVo);
empaccVo.setEmpId(empVo.getEmpId());
eaccBase.undateEacc(empaccVo);
}else{
empBase.addEmp2(empVo);//要先主鍵回填,才可以有empId,因為還沒有載入到資料庫表中
empaccVo.setEmpId(empVo.getEmpId());
eaccBase.addEacc(empaccVo);
}
sqlSession.commit();
// List<EmpVo> eList=empBase.listemp();
List<EmpVo4> eList=empBase.listEmp_EAcc_ETask_EDep_EStatus_If(empVo);
request.setAttribute("empList", eList);
request.getRequestDispatcher("EmpList.jsp").forward(request, response);
}要麼改為：
要麼初始化(因為status為0表示禁用或1表示啟用,所以-1才表示不選擇)為:
)
Opening JDBC Connection
Created connection 20026077.
Setting autocommit to false on JDBC Connection [[email protected]]
==> Preparing: insert into emp(empId,empName,password,age,sex,depId,job,status,remark) values(?,?,?,?,?,?,?,?,?);
==> Parameters: null, 111(String), 111(String), 111(Integer), 男(String), 6(Integer), 111(String), 1(Integer), 111(String)
十二月 18, 2018 8:57:45 下午 org.apache.catalina.core.StandardWrapperValve invoke
嚴重: Servlet.service() for servlet [empServlet] in context with path [/MyBatisQ] threw exception
org.apache.ibatis.exceptions.PersistenceException:
### Error updating database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Column 'empId' cannot be null
### The error may involve qiu.mapper.EmpDAO.addEmp2-Inline
### The error occurred while setting parameters
### SQL: insert into emp(empId,empName,password,age,sex,depId,job,status,remark) values(?,?,?,?,?,?,?,?,?);
### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Column 'empId' cannot be null
at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:200)
at org.apache.ibatis.session.defaults.DefaultSqlSession.insert(DefaultSqlSession.java:185)
at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:57)
at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:59)
at com.sun.proxy.$Proxy12.addEmp2(Unknown Source)
at qiu.servlet.EmpServlet.doPost(EmpServlet.java:96)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at qiu.base.EncodingFilter.doFilter(EncodingFilter.java:28)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:315)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Column 'empId' cannot be null
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.Util.getInstance(Util.java:408)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:935)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3973)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3909)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2527)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2680)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2490)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1858)
at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:1197)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.ibatis.logging.jdbc.PreparedStatementLogger.invoke(PreparedStatementLogger.java:59)
at com.sun.proxy.$Proxy10.execute(Unknown Source)
at org.apache.ibatis.executor.statement.PreparedStatementHandler.update(PreparedStatementHandler.java:46)
at org.apache.ibatis.executor.statement.RoutingStatementHandler.update(RoutingStatementHandler.java:74)
at org.apache.ibatis.executor.SimpleExecutor.doUpdate(SimpleExecutor.java:50)
at org.apache.ibatis.executor.BaseExecutor.update(BaseExecutor.java:117)
at org.apache.ibatis.executor.CachingExecutor.update(CachingExecutor.java:76)
at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:198)
... 29 more
————————————————************************分割線******************************——————————————
分享（其中複習MySQL查詢知識）：
{1}、【MyBatis學習筆記】8：增刪查改配置,結果集自動/自定義對映,主鍵回填/生成策略
（裡含 ‘ SELECT IF(MAX(id) is NULL,1,MAX(id)+2) FROM book ’ 語句，因為我不瞭解，所以找了：mysql 將null轉代為0（以及一些特殊用法） 
）
======擴充套件======》Oracle也有實現這樣的函式：
“ Oracle 中 decode 函式用法 ”或者“ oracle decode函式使用方法（百度經驗）”或者“ decode函式（百度百科） ”【第二連結‘與第一連結相似（都講解了decode(...）、sign(...）函式）但在‘舉例方面’相對更完善些’】
======擴充套件======》SQLServer也有實現這樣的方法：
資料庫--sqlserver--sqlserver 查詢 值如果為NULL則顯示0-解決方法
{2}、（mysql） select 時case、 if、 ifnull、nullif用法、sql_不使用or查詢 0 和null_ISNULL(a.status,0)=0 和 case when else end(sql學習之CASE WHEN THEN ELSE END的用法、case when then else end)、mysql 中 isnull 和 ifnull 判斷欄位是否為null、關於SQL語句中SUM函式返回NULL的解決辦法（裡含COALESCE 函式，講解不是很詳細，而且我在Navicat Premium中查詢，
