spring框架中的jackson解析json方法
从CSDN上的一人的博客中转的，他的博客地址为：http://blog.csdn.net/wyc_cs/article/details/6679722
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.writeObject(user); System.out.println(); System.out.println("使用ObjectMapper-----------"); // writeValue具有和writeObject相同的功能 objectMapper.writeValue(System.out, user); } public static void writeList2Json() throws IOException { List<User> userList = new ArrayList<User>(); userList.add(user); User u = new User(); u.setUid(10); u.setUname("archie"); u.setUpwd("123"); userList.add(u); objectMapper.writeValue(System.out, userList); } public static void writeMap2Json() { try { Map<String, Object> map = new HashMap<String, Object>(); User u = new User(); u.setUid(10); 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.writeObject(map); objectMapper.writeValue(System.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.writeBinary(str.getBytes()); // boolean jsonGenerator.writeBoolean(true); // null jsonGenerator.writeNull(); // float jsonGenerator.writeNumber(2.2f); // char jsonGenerator.writeRaw("c"); // String jsonGenerator.writeRaw(str, 5, 10); // String jsonGenerator.writeRawValue(str, 5, 5); // String jsonGenerator.writeString(str); jsonGenerator.writeTree(JsonNodeFactory.instance.POJONode(str)); 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.writeNumber(22);// 22 jsonGenerator.writeString("this is array");// this is array jsonGenerator.writeEndArray();// ] jsonGenerator.writeEndObject();// } User u = new User(); user.setUid(5); user.setUname("tom"); user.setUpwd("123"); user.setNumber(3.44); // 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.readValue(json, User.class); System.out.println(acc.getUid()); System.out.println(acc); } 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<LinkedHashMap<String, Object>> list = objectMapper.readValue( json, List.class); System.out.println(list.size()); for (int i = 0; i < list.size(); i++) { Map<String, Object> map = list.get(i); Set<String> set = map.keySet(); for (Iterator<String> it = set.iterator(); it.hasNext();) { String key = it.next(); System.out.println(key + ":" + map.get(key)); } } } 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.readValue(json, User[].class); System.out.println(arr.length); for (int i = 0; i < arr.length; i++) { System.out.println(arr[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<String, Map<String, Object>> maps = objectMapper.readValue(json, Map.class); System.out.println(maps.size()); Set<String> key = maps.keySet(); Iterator<String> iter = key.iterator(); while (iter.hasNext()) { String field = iter.next(); System.out.println(field + ":" + maps.get(field)); } } catch (JsonParseException e) { e.printStackTrace(); } catch (JsonMappingException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } public static void main(String[] args) { user = new User(); user.setUid(5); user.setUname("tom"); user.setUpwd("123"); user.setNumber(3.44); objectMapper = new ObjectMapper(); try { //jsonGenerator = objectMapper.getJsonFactory().createJsonGenerator(System.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 setNumber(double number) { this.number = number; } public int getUid() { return uid; } public void setUid(int uid) { this.uid = uid; } public String getUname() { return uname; } public void setUname(String uname) { this.uname = uname; } public String getUpwd() { return upwd; } public void setUpwd(String upwd) { this.upwd = upwd; } }