最近在做项目，需要用到json和java之间的交互，本人对json不是特别精通，于是开始搜索一些java平台的json类库。

发现了google的gson，带着一些好奇心，我开始使用了gson。

经过比较，gson和其他现有java json类库最大的不同时gson需要序列化得实体类不需要使用annotation来标识需要序列化得字段，

同时gson又可以通过使用annotation来灵活配置需要序列化的字段。

还有一款fastjson也不错执行性能更优，他们都是不依赖其他类库的，但是个人还是习惯用gson，呵呵。

不废话上代码看看吧

这是一个用户实体，里面包含了基本类型，数组和list和map类型，

都是大家常用的。

public class User {

	private int id;
	private String name;
	private boolean isAdmin;
	private String[] tels;
	private List<Bank> banks;
	private Map doSome;
	
	public User() {
		// TODO Auto-generated constructor stub
	}

	public User(int id, String name, boolean isAdmin, String[] tels,
			List<Bank> banks, Map doSome) {
		super();
		this.id = id;
		this.name = name;
		this.isAdmin = isAdmin;
		this.tels = tels;
		this.banks = banks;
		this.doSome = doSome;
	}

	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;
	}
	public boolean isAdmin() {
		return isAdmin;
	}
	public void setAdmin(boolean isAdmin) {
		this.isAdmin = isAdmin;
	}
	public String[] getTels() {
		return tels;
	}
	public void setTels(String[] tels) {
		this.tels = tels;
	}
	public List<Bank> getBanks() {
		return banks;
	}
	public void setBanks(List<Bank> banks) {
		this.banks = banks;
	}
	
	public Map getDoSome() {
		return doSome;
	}

	public void setDoSome(Map doSome) {
		this.doSome = doSome;
	}
	
	@Override
	public String toString() {
		return "id:"+id+",name:"+name+",isAdmin:"+
		isAdmin+",tels:"+tels[0]+",banks:"+banks.get(0).getBankName()+","
		+ banks.get(1).getBankName() + ",10点:" + doSome.get("10点");
	}

}

public class Bank {

	private Integer id;
	private String bankName;
	
	public Bank() {
		// TODO Auto-generated constructor stub
	}
	
	public Bank(Integer id, String bankName) {
		super();
		this.id = id;
		this.bankName = bankName;
	}

	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getBankName() {
		return bankName;
	}
	public void setBankName(String bankName) {
		this.bankName = bankName;
	}
	
}

/**
 * 测试gson
 * @author jelly
 *
 */
public class Test {

	public static void main(String[] args) {
		Gson gson = new Gson();
		//java复杂对象转json
		Bank b1 = new Bank(1,"中国银行卡");
		Bank b2 = new Bank(2,"工行银行卡");
		List<Bank> banks = new ArrayList<Bank>();
		banks.add(b1);banks.add(b2);
		Map map = new HashMap();
		map.put("10点", "出去卖萌!");
		User user1 = new User(1,"张三",false,new String[]{"130000000","150"},banks,map);
		String toString = gson.toJson(user1);
		System.out.println(toString);
		
		System.out.println("\n//--------------华丽的分割线--------------//\n");
		
		//json转java对象
		String json = "{'id':1,'name':'张三','isAdmin':false,'tels':['130','150'],'banks':[{'id':1,'bankName':'中国银行卡'},{'id':2,'bankName':'工行银行卡'}],'doSome':{'10点':'出去卖萌!'}}";
		User u = gson.fromJson(json, User.class);
		System.out.println(u);
	}
}

输出结果：

{"id":1,"name":"张三","isAdmin":false,"tels":["130000000","150"],"banks":[{"id":1,"bankName":"中国银行卡"},{"id":2,"bankName":"工行银行卡"}],"doSome":{"10点":"出去卖萌!"}}

//--------------华丽的分割线--------------//

id:1,name:张三,isAdmin:false,tels:130,banks:中国