gson序列話的時候,排除欄位工具類
/**
涉及所需要欄位的方法,排除欄位的方法,並呼叫相對應的方法輸出json格式的資料:如下所示
*/
第一步:
GsonUtils.java
package cn.itcast.oa.util;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonObject;
import org.apache.commons.io.IOUtils;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.security.InvalidParameterException;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* gson的工具類
*
* @author miles
*/
public class GsonUtils {
/**
* 將一個物件轉成json字串
*
* @param obj
* @return
*/
public static String toJson(Object obj) {
return toJsonExclude(obj);
}
/**
* 將一個物件轉成json字串並指定需要排除的屬性名稱列表
* 如果沒有指定屬性名稱集合,則將會全部轉換
* 預設時間會以時間戳的格式進行轉換
*
* @param obj
* @param exclusionFields
* @return String
*/
public static String toJsonExclude(Object obj, String... exclusionFields) {
validateJsonObject(obj);
//建立GsonBuilder
GsonBuilder builder = new GsonBuilder();
//設定時間格式
builder.registerTypeAdapter(Date.class, new DateConverter());
//設定需要被排除的屬性列表
if (exclusionFields != null && exclusionFields.length > 0) {
GsonExclusion gsonFilter = new GsonExclusion();
gsonFilter.addExclusionField(exclusionFields);
builder.setExclusionStrategies(gsonFilter);
}
//建立Gson並進行轉換
Gson gson = builder.create();
return gson.toJson(obj);
}
/**
* 將一個物件轉成json字串並指定需要需要轉換的屬性名稱列表
* 如果沒有指定屬性名稱集合,則將會全部轉換
* 預設時間會以yyyy-MM-dd HH:mm:ss的格式進行轉換
*
* @param obj
* @param includeFields
* @return
*/
public static String toJsonInclude(Object obj, String... includeFields) {
validateJsonObject(obj);
//建立GsonBuilder
GsonBuilder builder = new GsonBuilder();
//設定時間格式
builder.registerTypeAdapter(Date.class, new DateConverter());
//設定需要轉換的屬性名稱
if (includeFields != null && includeFields.length > 0) {
GsonInclusion gsonFilter = new GsonInclusion();
gsonFilter.addInclusionFields(includeFields);
builder.setExclusionStrategies(gsonFilter);
}
//建立Gson並進行轉換
Gson gson = builder.create();
String json = gson.toJson(obj);
System.out.println("json;;;;"+json);
return json;
}
/**
* 通過response輸出json資料
*
* @param response HttpServletResponse物件
* @param json json字串
*/
public static void printJson(HttpServletResponse response, String json) {
PrintWriter writer = null;
try {
response.setContentType("application/json");
writer = response.getWriter();
writer.print(json);
} catch (IOException e) {
e.printStackTrace();
} finally {
if (writer != null) {
writer.close();
}
}
}
public static Map<String, Object> convertJson2Map(String json) {
if (json == null) return null;
Gson gson = new GsonBuilder().create();
return gson.fromJson(json, HashMap.class);
}
public static void printJson(HttpServletResponse response, String key, String value) {
JsonObject jsonObject = new JsonObject();
jsonObject.addProperty(key, value);
printJson(response, jsonObject.toString());
}
/**
* 將一個集合轉成{data:[]}形式的物件
*
* @param response
* @param data
*/
public static void printCollectionJson(HttpServletResponse response, List data, String... includes) {
String json = toCollectionJson(data, includes);
printJson(response, json);
}
/**
* 將一個集合轉成{data:[]}形式的字串
*
* @param data
* @return
*/
public static String toCollectionJson(List data, String... includes) {
Map<String, List> map = new HashMap<String, List>();
map.put("data", data);
return toJsonInclude(map, includes);
}
public static void printJson(HttpServletResponse response, String key, Integer value) {
JsonObject jsonObject = new JsonObject();
jsonObject.addProperty(key, value);
printJson(response, jsonObject.toString());
}
public static void printJson(HttpServletResponse response, String key, Float value) {
JsonObject jsonObject = new JsonObject();
jsonObject.addProperty(key, value);
printJson(response, jsonObject.toString());
}
public static void printJson(HttpServletResponse response, String key, Double value) {
JsonObject jsonObject = new JsonObject();
jsonObject.addProperty(key, value);
printJson(response, jsonObject.toString());
}
public static void printJson(HttpServletResponse response, String key, Boolean value) {
JsonObject jsonObject = new JsonObject();
jsonObject.addProperty(key, value);
printJson(response, jsonObject.toString());
}
/**
* 通過response輸出json資料
*
* @param response HttpServletResponse物件
* @param obj object
*/
public static void printJsonObject(HttpServletResponse response, Object obj) {
if (obj == null) return;
if (obj instanceof String) {
printJson(response, (String) obj);
return;
}
String json = toJson(obj);
printJson(response, json);
}
public static void printError(HttpServletResponse response, String reason) {
JsonObject jsonObject = new JsonObject();
jsonObject.addProperty("error", reason);
printJson(response, jsonObject.toString());
}
private static void validateJsonObject(Object obj) {
if (obj == null) {
throw new NullPointerException("要轉成json的物件不能為空!");
}
if (obj instanceof String || obj instanceof Number || obj instanceof Boolean) {
throw new RuntimeException("要轉成json字串的必須是複雜(引用)型別的物件!");
}
}
/**
* 從request body中取出資料流(json字串),並進行utf-8轉碼後,使用Gson轉換成指定型別的物件
* 如果request、clazz為空,則丟擲異常
*
* @param request 包含請求體的request物件
* @param clazz 要轉成的物件的型別
* @param excludeFields(可選,要排除的欄位)
* @param <T>
* @return clazz指定的型別
*/
public static <T> T wrapDataToEntity(HttpServletRequest request, Class<T> clazz, String... excludeFields) {
if (request == null || clazz == null) {
throw new InvalidParameterException("引數不能為空!");
}
String data = null;
try {
data = IOUtils.toString(request.getInputStream(), "utf-8");
} catch (IOException e) {
e.printStackTrace();
}
GsonBuilder builder = new GsonBuilder();
builder.registerTypeAdapter(Date.class, new DateConverter());
//要排除的欄位
if (excludeFields != null && excludeFields.length > 0) {
GsonExclusion exclusions = new GsonExclusion();
exclusions.addExclusionField(excludeFields);
builder.setExclusionStrategies(exclusions);
}
Gson gson = builder.create();
T entity = gson.fromJson(data, clazz);
return entity;
}
public static void printSuccess(HttpServletResponse response) {
printJson(response, "success", true);
}
}
第二步,方法的呼叫如下所示
/**
* 根據條件查詢所有符合條件的選單,並組裝成樹,返回
*/
public String jsonQuery() {
String id=this.getRequest().getParameter("id");
List<RegionVo> regions=regionService.jsonQuery(id);
//this.getRequest().setAttribute("regions", regions);
//GsonUtils.printJson(getResponse(), GsonUtils.toJsonInclude(regions, "id", "name", "isParent"));
String json = GsonUtils.toJsonInclude(regions, "id","name","children","path","open");
System.out.println("jsonAction:"+json);
GsonUtils.printJson(getResponse(), json);
return null;
}