如何使用Jackson解析JSON示例
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package com.bbs.utils.json;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.codehaus.jackson.JsonGenerator;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.node.JsonNodeFactory;
public class JacksonTest
private static JsonGenerator jsonGenerator = null;
private static ObjectMapper objectMapper = null;
private static User user = null;
public static void writeEntity2Json throws IOException
System.out.println"使用JsonGenerator转化实体为json串-------------";
// writeObject可以转换java对象，eg:JavaBean/Map/List/Array等
jsonGenerator.writeObjectuser;
System.out.println;
System.out.println"使用ObjectMapper-----------";
// writeValue具有和writeObject相同的功能
objectMapper.writeValueSystem.out, user;
public static void writeList2Json throws IOException
List userList = new ArrayList;
userList.adduser;
User u = new User;
u.setUid10;
u.setUname"archie";
u.setUpwd"123";
userList.addu;
objectMapper.writeValueSystem.out, userList;
public static void writeMap2Json
try
Map map = new HashMap;
User u = new User;
u.setUid10;
u.setUname"archie";
u.setUpwd"123";
map.put"uid", u.getUid;
map.put"uname", u.getUname;
map.put"upwd", u.getUpwd;
System.out.println"jsonGenerator";
jsonGenerator.writeObjectmap;
objectMapper.writeValueSystem.out, map;
catch IOException e
e.printStackTrace;
public static void writeOthersJSON
try
String[] arr = "a", "b", "c" ;
System.out.println"jsonGenerator";
String str = "hello world jackson!";
// byte
jsonGenerator.writeBinarystr.getBytes;
// boolean
jsonGenerator.writeBooleantrue;
// null
jsonGenerator.writeNull;
// float
jsonGenerator.writeNumber2.2f;
// char
jsonGenerator.writeRaw"c";
// String
jsonGenerator.writeRawstr, 5, 10;
// String
jsonGenerator.writeRawValuestr, 5, 5;
// String
jsonGenerator.writeStringstr;
jsonGenerator.writeTreeJsonNodeFactory.instance.POJONodestr;
System.out.println;
// Object
jsonGenerator.writeStartObject;//
jsonGenerator.writeObjectFieldStart"user";// user:
jsonGenerator.writeStringField"name", "jackson";// name:jackson
jsonGenerator.writeBooleanField"sex", true;// sex:true
jsonGenerator.writeNumberField"age", 22;// age:22
jsonGenerator.writeEndObject;
jsonGenerator.writeArrayFieldStart"infos";// infos:[
jsonGenerator.writeNumber22;// 22
jsonGenerator.writeString"this is array";// this is array
jsonGenerator.writeEndArray;// ]
jsonGenerator.writeEndObject;//
User u = new User;
user.setUid5;
user.setUname"tom";
user.setUpwd"123";
user.setNumber3.44;
// complex Object
jsonGenerator.writeStartObject;//
jsonGenerator.writeObjectField"uid", u;// user:bean
jsonGenerator.writeObjectField"infos", arr;// infos:[array]
jsonGenerator.writeEndObject;//
catch Exception e
e.printStackTrace;
/**
* JSON字符串转换为对象
*/
public static void readJson2Entity
String json = "\"uid\":5,\"uname\":\"tom\",\"number\":3.44,\"upwd\":\"123\"";
try
User acc = objectMapper.readValuejson, User.class;
System.out.printlnacc.getUid;
System.out.printlnacc;
catch JsonParseException e
e.printStackTrace;
catch JsonMappingException e
e.printStackTrace;
catch IOException e
e.printStackTrace;
/**
* JSON转换为List对象
*/
public static void readJson2List
String json = "[\"uid\":1,\"uname\":\"www\",\"number\":234,\"upwd\":\"456\","
+ "\"uid\":5,\"uname\":\"tom\",\"number\":3.44,\"upwd\":\"123\"]";
try
List> list = objectMapper.readValue
json, List.class;
System.out.printlnlist.size;
for int i = 0; i < list.size; i++
Map map = list.geti;
Set set = map.keySet;
for Iterator it = set.iterator; it.hasNext;
String key = it.next;
System.out.printlnkey + ":" + map.getkey;
catch JsonParseException e
e.printStackTrace;
catch JsonMappingException e
e.printStackTrace;
catch IOException e
e.printStackTrace;
/**
* JSON转换为数组对象
*/
public static void readJson2Array
String json = "[\"uid\":1,\"uname\":\"www\",\"number\":234,\"upwd\":\"456\","
+ "\"uid\":2,\"uname\":\"sdfsdf\",\"number\":4745,\"upwd\":\"23456\"]";
try
User[] arr = objectMapper.readValuejson, User[].class;
System.out.printlnarr.length;
for int i = 0; i < arr.length; i++
System.out.printlnarr[i];
catch JsonParseException e
e.printStackTrace;
catch JsonMappingException e
e.printStackTrace;
catch IOException e
e.printStackTrace;
/**
* JSON转换为Map对象
*/
public static void readJson2Map
String json = "\"success\":true,\"A\":\"address\": \"address2\",\"name\":\"haha2\",\"id\":2,\"email\":\"email2\","+
"\"B\":\"address\":\"address\",\"name\":\"haha\",\"id\":1,\"email\":\"email\"";
try
Map> maps = objectMapper.readValuejson, Map.class;
System.out.printlnmaps.size;
Set key = maps.keySet;
Iterator iter = key.iterator;
while iter.hasNext
String field = iter.next;
System.out.printlnfield + ":" + maps.getfield;
catch JsonParseException e
e.printStackTrace;
catch JsonMappingException e
e.printStackTrace;
catch IOException e
e.printStackTrace;
public static void mainString[] args
user = new User;
user.setUid5;
user.setUname"tom";
user.setUpwd"123";
user.setNumber3.44;
objectMapper = new ObjectMapper;
try
//jsonGenerator = objectMapper.getJsonFactory.createJsonGeneratorSystem.out, JsonEncoding.UTF8;
// writeEntity2Json;
// writeMap2Json;
// writeList2Json;
// writeOthersJSON;
// readJson2Entity;
// readJson2List;
// readJson2Array;
readJson2Map;
catch Exception e
e.printStackTrace;
========================User.java==============
package com.bbs.utils.json;
public class User
private int uid;
private String uname;
private String upwd;
private double number;
public double getNumber
return number;
public void setNumberdouble number
this.number = number;
public int getUid
return uid;
public void setUidint uid
this.uid = uid;
public String getUname
return uname;
public void setUnameString uname
this.uname = uname;
public String getUpwd
return upwd;
public void setUpwdString upwd
this.upwd = upwd;