json <--->List集合,实体类 之间的相互转换

json所依赖的jar包
http://files.cnblogs.com/files/wenjie123/json_jar%E5%8C%85.rar

package com.hp.svse;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

import net.sf.json.JsonConfig;
import net.sf.json.processors.JsonValueProcessor;
/**
* Timestamp 处理器
*/
public class JsonDateValueProcessor implements JsonValueProcessor {

private String formatDateTime ="yyyy-MM-dd HH:mm:ss";
private String formatDate ="yyyy-MM-dd";
public Object processArrayValue(Object value, JsonConfig config) {
return process(value);
}

public Object processObjectValue(String key, Object value, JsonConfig config) {
return process(value);
}

private Object process(Object value){

if(value instanceof Date){
SimpleDateFormat sdf ;
if(value.toString().length()<=11||value.toString().indexOf("00:00:00.0")>=0){
sdf= new SimpleDateFormat(formatDate,Locale.UK);
}else{
sdf= new SimpleDateFormat(formatDateTime,Locale.UK);
}
return sdf.format(value);
}
return value == null ? "" : value.toString();
}
}

package com.hp.svse;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import net.sf.json.JsonConfig;

public class JsonTest {
public static void main(String[] args) {

/**
* 将对象集合转换成JSON格式的字符串
*/
List<Student> students = new ArrayList<Student>();
students.add(new Student("小明1", "男", "湖北", "SVSE"));
students.add(new Student("小明2", "女", "广东", "GIS"));
students.add(new Student("小明3", "男", "香港", "3G"));
JsonTest jsonTest = new JsonTest();
String json = jsonTest.beanListToJSON(students);
System.out.println(json);
/**
* 输出结果：
* [
*     {"sex":"男","address":"湖北","stuname":"小明1","classname":"SVSE","smallStudents":[]},
*     {"sex":"女","address":"广东","stuname":"小明2","classname":"GIS","smallStudents":[]},
*     {"sex":"男","address":"香港","stuname":"小明3","classname":"3G","smallStudents":[]}
* ]
*/

/**
* 将json字符串转换成json对象  再讲json对象转换成实体对象bean
*/
String bookCotentjsonStr = "{\"sex\":\"男\",\"address\":\"湖北\",\"stuname\":\"小明1\",\"classname\":\"SVSE\"}";
JSONObject bookCotentjson = JSONObject.fromObject(bookCotentjsonStr);
Student student = (Student) JSONObject.toBean(bookCotentjson, Student.class);
System.out.println(student);
/**
* 输出结果：Student [address=湖北, classname=SVSE, sex=男, stuname=小明1]
*/

/**
* 将对象转换成JSON格式的字符串 适用于单个对象(单个对象里可以包含List<T>)的转换
*/
List<SmallStudent> smallStudents = new ArrayList<SmallStudent>();
for (int i = 0; i < 3; i++) {
SmallStudent smallStudent = new SmallStudent();
smallStudent.setName("小学生"+i);
smallStudent.setAge("1"+i);
smallStudents.add(smallStudent);
}
Student student2 = new Student("小明", "男", "武汉", "svse",smallStudents);
String jsonStr = jsonTest.beanToJSON(student2);
System.out.println(jsonStr);
/**
* 输出结果：
* {"sex":"男","address":"武汉","stuname":"小明","classname":"svse","smallStudents":[{"sex":"","age":"10","name":"小学生0"},{"sex":"","age":"11","name":"小学生1"},{"sex":"","age":"12","name":"小学生2"}]}
*/

}
/**
* 将集合转换成JSON格式的字符串
*/
public <T> String beanListToJSON(List<T> t) {
String json = "";
JsonConfig jsonConfig = new JsonConfig();
jsonConfig.registerJsonValueProcessor(Date.class,
new JsonDateValueProcessor());
if(t!=null){
json = JSONArray.fromObject(t, jsonConfig).toString();
}else{
json="[]";
}
return json;
}

/**
* 将对象转换成JSON格式的字符串 适用于单个对象(单个对象里可以包含List<T>)的转换
*/
public <T> String beanToJSON(T t) {
String json = "";
JsonConfig jsonConfig = new JsonConfig();
jsonConfig.registerJsonValueProcessor(Date.class,
new JsonDateValueProcessor());
if(t!=null){
json = JSONObject.fromObject(t, jsonConfig).toString();
}else{
json="[]";
}
return json;
}
}

package com.hp.svse;

import java.util.List;

public class Student {
private String stuname;
private String sex;
private String address;
private String classname;
private List<SmallStudent> smallStudents;

public Student(String stuname, String sex, String address, String classname,List<SmallStudent> smallStudents) {
super();
this.stuname = stuname;
this.sex = sex;
this.address = address;
this.classname = classname;
this.smallStudents = smallStudents;
}
public Student(String stuname, String sex, String address, String classname) {
super();
this.stuname = stuname;
this.sex = sex;
this.address = address;
this.classname = classname;
}
public Student() {
super();
}

public String getStuname() {
return stuname;
}
public void setStuname(String stuname) {
this.stuname = stuname;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String getClassname() {
return classname;
}
public void setClassname(String classname) {
this.classname = classname;
}

public List<SmallStudent> getSmallStudents() {
return smallStudents;
}

public void setSmallStudents(List<SmallStudent> smallStudents) {
this.smallStudents = smallStudents;
}

@Override
public String toString() {
return "Student [address=" + address + ", classname=" + classname
+ ", sex=" + sex + ", stuname=" + stuname + "]";
}

}

package com.hp.svse;

public class SmallStudent {
private String name;
private String age;
private String sex;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
@Override
public String toString() {
return "SmallStudent [age=" + age + ", name=" + name + ", sex=" + sex
+ "]";
}
}