json、javaBean、xml互轉的幾種工具
阿新 • • 發佈：2019-02-18
工作中經常要用到Json、JavaBean、Xml之間的相互轉換，用到了很多種方式，這裡做下總結，以供參考。
現在主流的轉換工具有json-lib、jackson、fastjson等，我為大家一一做簡單介紹，主要還是以程式碼形式貼出如何簡單應用這些工具的，更多高階功能還需大家深入研究。
首先是json-lib，算是很早的轉換工具了，用的人很多，說實在現在完全不適合了，缺點比較多，依賴的第三方實在是比較多，效率低下，API也比較繁瑣，說他純粹是因為以前的老專案很多人都用到它。不廢話，開始上程式碼。
需要的maven依賴：
<dependency> <groupId>net.sf.json-lib</groupId> <artifactId>json-lib</artifactId> <version>2.4</version> <classifier>jdk15</classifier> </dependency> <dependency> <groupId>xom</groupId> <artifactId>xom</artifactId> <version>1.1</version> </dependency> <dependency> <groupId>xalan</groupId> <artifactId>xalan</artifactId> <version>2.7.1</version> </dependency>
使用json-lib實現多種轉換
import java.text.SimpleDateFormat;import java.util.Date; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Map.Entry; import javax.swing.text.Document; import net.sf.ezmorph.Morpher; import net.sf.ezmorph.MorpherRegistry; import net.sf.ezmorph.bean.BeanMorpher; import net.sf.ezmorph.object.DateMorpher; import net.sf.json.JSON; import net.sf.json.JSONArray; import net.sf.json.JSONObject; import net.sf.json.JSONSerializer; import net.sf.json.JsonConfig; import net.sf.json.processors.JsonValueProcessor; import net.sf.json.util.CycleDetectionStrategy; import net.sf.json.util.JSONUtils; import net.sf.json.xml.XMLSerializer; /** * json-lib utils * @author magic_yy * @see json-lib.sourceforge.net/ * @see https://github.com/aalmiray/Json-lib * */ public class JsonLibUtils { public static JsonConfig config = new JsonConfig(); static{ config.setCycleDetectionStrategy(CycleDetectionStrategy.LENIENT);//忽略迴圈，避免死迴圈 config.registerJsonValueProcessor(Date.class, new JsonValueProcessor() {//處理Date日期轉換 @Override public Object processObjectValue(String arg0, Object arg1, JsonConfig arg2) { SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); Date d=(Date) arg1; return sdf.format(d); } @Override public Object processArrayValue(Object arg0, JsonConfig arg1) { return null; } }); } /** * java object convert to json string */ public static String pojo2json(Object obj){ return JSONObject.fromObject(obj,config).toString();//可以用toString(1)來實現格式化，便於閱讀 } /** * array、map、Javabean convert to json string */ public static String object2json(Object obj){ return JSONSerializer.toJSON(obj).toString(); } /** * xml string convert to json string */ public static String xml2json(String xmlString){ XMLSerializer xmlSerializer = new XMLSerializer(); JSON json = xmlSerializer.read(xmlString); return json.toString(); } /** * xml document convert to json string */ public static String xml2json(Document xmlDocument){ return xml2json(xmlDocument.toString()); } /** * json string convert to javaBean * @param <T> */ @SuppressWarnings("unchecked") public static <T> T json2pojo(String jsonStr,Class<T> clazz){ JSONObject jsonObj = JSONObject.fromObject(jsonStr); T obj = (T) JSONObject.toBean(jsonObj, clazz); return obj; } /** * json string convert to map */ public static Map<String,Object> json2map(String jsonStr){ JSONObject jsonObj = JSONObject.fromObject(jsonStr); Map<String,Object> result = (Map<String, Object>) JSONObject.toBean(jsonObj, Map.class); return result; } /** * json string convert to map with javaBean */ public static <T> Map<String,T> json2map(String jsonStr,Class<T> clazz){ JSONObject jsonObj = JSONObject.fromObject(jsonStr); Map<String,T> map = new HashMap<String, T>(); Map<String,T> result = (Map<String, T>) JSONObject.toBean(jsonObj, Map.class, map); MorpherRegistry morpherRegistry = JSONUtils.getMorpherRegistry(); Morpher dynaMorpher = new BeanMorpher(clazz,morpherRegistry); morpherRegistry.registerMorpher(dynaMorpher); morpherRegistry.registerMorpher(new DateMorpher(new String[]{ "yyyy-MM-dd HH:mm:ss" })); for (Entry<String,T> entry : result.entrySet()) { map.put(entry.getKey(), (T)morpherRegistry.morph(clazz, entry.getValue())); } return map; } /** * json string convert to array */ public static Object[] json2arrays(String jsonString) { JSONArray jsonArray = (JSONArray) JSONSerializer.toJSON(jsonString); // JSONArray jsonArray = JSONArray.fromObject(jsonString); JsonConfig jsonConfig = new JsonConfig(); jsonConfig.setArrayMode(JsonConfig.MODE_OBJECT_ARRAY); Object[] objArray = (Object[]) JSONSerializer.toJava(jsonArray,jsonConfig); return objArray; } /** * json string convert to list * @param <T> */ @SuppressWarnings({ "unchecked", "deprecation" }) public static <T> List<T> json2list(String jsonString, Class<T> pojoClass){ JSONArray jsonArray = JSONArray.fromObject(jsonString); return JSONArray.toList(jsonArray, pojoClass); } /** * object convert to xml string */ public static String obj2xml(Object obj){ XMLSerializer xmlSerializer = new XMLSerializer(); return xmlSerializer.write(JSONSerializer.toJSON(obj)); } /** * json string convert to xml string */ public static String json2xml(String jsonString){ XMLSerializer xmlSerializer = new XMLSerializer(); xmlSerializer.setTypeHintsEnabled(true);//是否保留元素型別標識，預設true xmlSerializer.setElementName("e");//設定元素標籤，預設e xmlSerializer.setArrayName("a");//設定陣列標籤，預設a xmlSerializer.setObjectName("o");//設定物件標籤，預設o return xmlSerializer.write(JSONSerializer.toJSON(jsonString)); } }
測試程式碼如下：
import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import net.sf.ezmorph.test.ArrayAssertions; import org.junit.Assert; import org.junit.Test; public class JsonLibUtilsTest { @Test public void pojo2json_test(){ User user = new User(1, "張三"); String json = JsonLibUtils.pojo2json(user); Assert.assertEquals("{\"id\":1,\"name\":\"張三\"}", json); } @Test public void object2json_test(){ int[] intArray = new int[]{1,4,5}; String json = JsonLibUtils.object2json(intArray); Assert.assertEquals("[1,4,5]", json); User user1 = new User(1,"張三"); User user2 = new User(2,"李四"); User[] userArray = new User[]{user1,user2}; String json2 = JsonLibUtils.object2json(userArray); Assert.assertEquals("[{\"id\":1,\"name\":\"張三\"},{\"id\":2,\"name\":\"李四\"}]", json2); List<User> userList = new ArrayList<>(); userList.add(user1); userList.add(user2); String json3 = JsonLibUtils.object2json(userList); Assert.assertEquals("[{\"id\":1,\"name\":\"張三\"},{\"id\":2,\"name\":\"李四\"}]", json3); //這裡的map的key必須為String型別 Map<String,Object> map = new HashMap<>(); map.put("id", 1); map.put("name", "張三"); String json4 = JsonLibUtils.object2json(map); Assert.assertEquals("{\"id\":1,\"name\":\"張三\"}", json4); Map<String,User> map2 = new HashMap<>(); map2.put("user1", user1); map2.put("user2", user2); String json5 = JsonLibUtils.object2json(map2); Assert.assertEquals("{\"user2\":{\"id\":2,\"name\":\"李四\"},\"user1\":{\"id\":1,\"name\":\"張三\"}}", json5); } @Test public void xml2json_test(){ String xml1 = "<User><id>1</id><name>張三</name></User>"; String json = JsonLibUtils.xml2json(xml1); Assert.assertEquals("{\"id\":\"1\",\"name\":\"張三\"}", json); String xml2 = "<Response><CustID>1300000428</CustID><Items><Item><Sku_ProductNo>sku_0004</Sku_ProductNo></Item><Item><Sku_ProductNo>0005</Sku_ProductNo></Item></Items></Response>"; String json2 = JsonLibUtils.xml2json(xml2); //處理陣列時expected是處理結果，但不是我們想要的格式 String expected = "{\"CustID\":\"1300000428\",\"Items\":[{\"Sku_ProductNo\":\"sku_0004\"},{\"Sku_ProductNo\":\"0005\"}]}"; Assert.assertEquals(expected, json2); //實際上我們想要的是expected2這種格式,所以用json-lib來實現含有陣列的xml to json是不行的 String expected2 = "{\"CustID\":\"1300000428\",\"Items\":{\"Item\":[{\"Sku_ProductNo\":\"sku_0004\"},{\"Sku_ProductNo\":\"0005\"}]}}"; Assert.assertEquals(expected2, json2); } @Test public void json2arrays_test(){ String json = "[\"張三\",\"李四\"]"; Object[] array = JsonLibUtils.json2arrays(json); Object[] expected = new Object[] { "張三", "李四" }; ArrayAssertions.assertEquals(expected, array); //無法將JSON字串轉換為物件陣列 String json2 = "[{\"id\":1,\"name\":\"張三\"},{\"id\":2,\"name\":\"李四\"}]"; Object[] array2 = JsonLibUtils.json2arrays(json2); User user1 = new User(1,"張三"); User user2 = new User(2,"李四"); Object[] expected2 = new Object[] { user1, user2 }; ArrayAssertions.assertEquals(expected2, array2); } @Test public void json2list_test(){ String json = "[\"張三\",\"李四\"]"; List<String> list = JsonLibUtils.json2list(json, String.class); Assert.assertTrue(list.size()==2&&list.get(0).equals("張三")&&list.get(1).equals("李四")); String json2 = "[{\"id\":1,\"name\":\"張三\"},{\"id\":2,\"name\":\"李四\"}]"; List<User> list2 = JsonLibUtils.json2list(json2, User.class); Assert.assertTrue(list2.size()==2&&list2.get(0).getId()==1&&list2.get(1).getId()==2); } @Test public void json2pojo_test(){ String json = "{\"id\":1,\"name\":\"張三\"}"; User user = (User) JsonLibUtils.json2pojo(json, User.class); Assert.assertEquals(json, user.toString()); } @Test public void json2map_test(){ String json = "{\"id\":1,\"name\":\"張三\"}"; Map map = JsonLibUtils.json2map(json); int id = Integer.parseInt(map.get("id").toString()); String name = map.get("name").toString(); System.out.println(name); Assert.assertTrue(id==1&&name.equals("張三")); String json2 = "{\"user2\":{\"id\":2,\"name\":\"李四\"},\"user1\":{\"id\":1,\"name\":\"張三\"}}"; Map map2 = JsonLibUtils.json2map(json2, User.class); System.out.println(map2); } @Test public void json2xml_test(){ String json = "{\"id\":1,\"name\":\"張三\"}"; String xml = JsonLibUtils.json2xml(json); Assert.assertEquals("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\r\n<o><id type=\"number\">1</id><name type=\"string\">張三</name></o>\r\n", xml); System.out.println(xml); String json2 = "[{\"id\":1,\"name\":\"張三\"},{\"id\":2,\"name\":\"李四\"}]"; String xml2 = JsonLibUtils.json2xml(json2); System.out.println(xml2); Assert.assertEquals("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\r\n<a><e class=\"object\"><id type=\"number\">1</id><name type=\"string\">張三</name></e><e class=\"object\"><id type=\"number\">2</id><name type=\"string\">李四</name></e></a>\r\n", xml2); } public static class User{ private int id; private String name; public User() { } public User(int id, String name) { this.id = id; this.name = name; } @Override public String toString() { return "{\"id\":"+id+",\"name\":\""+name+"\"}"; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } } }
json-lib在XML轉換為JSON在有陣列的情況下會有問題，還有在JSON轉換為XML時都會有元素標識如<o><a><e>等，在一般情況下我們可能都不需要，暫時還不知道如何過濾這些元素名稱。
因為json-lib的種種缺點，基本停止了更新，也不支援註解轉換，後來便有了jackson流行起來，它比json-lib的轉換效率要高很多，依賴很少，社群也比較活躍
我們依舊開始上程式碼，首先是它的依賴：
<dependency> <groupId>com.fasterxml.jackson.dataformat</groupId> <artifactId>jackson-dataformat-xml</artifactId> <version>2.1.3</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.1.3</version> <type>java-source</type> <scope>compile</scope> </dependency>
這裡我要說下，有很多基於jackson的工具，大家可以按照自己的實際需求來需找對應的依賴，我這裡為了方便轉換xml所以用了dataformat-xml和databind
使用jackson實現多種轉換：
package cn.yangyong.fodder.util; import java.io.StringWriter; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Map.Entry; import com.fasterxml.jackson.core.JsonGenerator; import com.fasterxml.jackson.core.JsonParser; import com.fasterxml.jackson.core.type.TypeReference; import com.fasterxml.jackson.databind.JsonNode; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.dataformat.xml.XmlMapper; public class JacksonUtils { private static ObjectMapper objectMapper = new ObjectMapper(); private static XmlMapper xmlMapper = new XmlMapper(); /** * javaBean,list,array convert to json string */ public static String obj2json(Object obj) throws Exception{ return objectMapper.writeValueAsString(obj); } /** * json string convert to javaBean */ public static <T> T json2pojo(String jsonStr,Class<T> clazz) throws Exception{ return objectMapper.readValue(jsonStr, clazz); } /** * json string convert to map */ public static <T> Map<String,Object> json2map(String jsonStr)throws Exception{ return objectMapper.readValue(jsonStr, Map.class); } /** * json string convert to map with javaBean */ public static <T> Map<String,T> json2map(String jsonStr,Class<T> clazz)throws Exception{ Map<String,Map<String,Object>> map = objectMapper.readValue(jsonStr, new TypeReference<Map<String,T>>() { }); Map<String,T> result = new HashMap<String, T>(); for (Entry<String, Map<String,Object>> entry : map.entrySet()) { result.put(entry.getKey(), map2pojo(entry.getValue(), clazz)); } return result; } /** * json array string convert to list with javaBean */ public static <T> List<T> json2list(String jsonArrayStr,Class<T> clazz)throws Exception{ List<Map<String,Object>> list = objectMapper.readValue(jsonArrayStr, new TypeReference<List<T>>() { }); List<T> result = new ArrayList<>(); for (Map<String, Object> map : list) { result.add(map2pojo(map, clazz)); } return result; } /** * map convert to javaBean */ public static <T> T map2pojo(Map map,Class<T> clazz){ return objectMapper.convertValue(map, clazz); } /** * json string convert to xml string */ public static String json2xml(String jsonStr)throws Exception{ JsonNode ro