java中解析一个json串，本文详细介绍了安卓原生的解析以及用fastjson解析

在java或安卓中解析JSON有很多种方式，可以用谷歌给安卓提供的原生的解析方式解析安卓，也可以选择第三方类库，一些比较流行的解析方式如fastjson，Gson等，本文就简单介绍一下java工程中fastjson解析json数据。在介绍fastjson解析之前，我想先给大家用谷歌给安卓提供的原生解析方式解析一个JSON数据串。

（一）google原生的解析方式：

用原生的解析方式需要用到一些google提供的类库，在你的工程下新建一个org.json包，然后可以从https://github.com/stleary/JSON-java下载其提供的java解析JSON的类库

然后把这些下载好的类复制到org.json包下，如下图：

给出json串如下：

{"firstName":"John","lastName":"Smith","address":{"streetAddress":"奥运村西",
"city":"北京","postalCode":"100019","state":"北京"},
"phoneNumber":[{"number":" 10086","type":"home"},{"number":" 10010","type":"fax"}],"sex":"male","age":25}

{...}里面的是一个JSONObject，而[...]是一个JSONArray

由JSON字符串我们可以定义出实体类如下：

public class User {
    private String firstName;
    private String lastName;
    private String sex;
    private int age;
    private Address address;
    private List<Phone> phoneNumber;

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }

    public List<Phone> getPhoneNumber() {
        return phoneNumber;
    }

    public void setPhoneNumber(List<Phone> phoneNumber) {
        this.phoneNumber = phoneNumber;
    }
}

public class Address {
    private String streetAddress;
    private String city;
    private String state;
    private String postalCode;

    public String getStreetAddress() {
        return streetAddress;
    }

    public void setStreetAddress(String streetAddress) {
        this.streetAddress = streetAddress;
    }

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }

    public String getPostalCode() {
        return postalCode;
    }

    public void setPostalCode(String postalCode) {
        this.postalCode = postalCode;
    }
}

public class Phone {
    private String type;
    private String number;

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public String getNumber() {
        return number;
    }

    public void setNumber(String number) {
        this.number = number;
    }
}

将json字符串解析到实体类里面

public class TestJson02 {
    public static void main(String[] args) {
        String str = "{\"firstName\":\"John\",\"lastName\":\"Smith\",\"address\":{\"streetAddress\":\"奥运村西\",\"city\":\"北京\",\"postalCode\":\"100019\",\"state\":\"北京\"},\"phoneNumber\":[{\"number\":\" 10086\",\"type\":\"home\"},{\"number\":\" 10010\",\"type\":\"fax\"}],\"sex\":\"male\",\"age\":25}\n";
        User user = parserUser(str);
        System.out.println(toJSONString(user));
    }
    private static String toJSONString(User user) {
        JSONObject userObj = new JSONObject();
        userObj.put("firstName", user.getFirstName());
        userObj.put("lastName", user.getLastName());
        userObj.put("sex", user.getSex());
        userObj.put("age", user.getAge());
        JSONObject addressObj = new JSONObject();
        Address address = user.getAddress();
        addressObj.put("streetAddress", address.getStreetAddress());
        addressObj.put("city", address.getCity());
        addressObj.put("state", address.getState());
        addressObj.put("postalCode", address.getPostalCode());
        userObj.put("address", addressObj);
        JSONArray phoneNumber = new JSONArray();
        List<Phone> phones = user.getPhoneNumber();
        for (Phone phone : phones) {
            JSONObject number = new JSONObject();
            number.put("type", phone.getType());
            number.put("number", phone.getNumber());
            phoneNumber.put(number);
        }
        userObj.put("phoneNumber", phoneNumber);
        return userObj.toString();
    }
    private static User parserUser(String str) {
        JSONObject object = new JSONObject(str);
        User user = new User();
        user.setFirstName(object.optString("firstName"));
        user.setLastName(object.optString("lastName"));
        user.setSex(object.optString("sex"));
        user.setAge(object.optInt("age"));
        JSONObject addressObj = object.optJSONObject("address");
        Address address = new Address();
        address.setStreetAddress(addressObj.optString("streetAddress"));
        address.setCity(addressObj.optString("city"));
        address.setState(addressObj.optString("state"));
        address.setPostalCode(addressObj.optString("postalCode"));
        user.setAddress(address);
        List<Phone> phones = new ArrayList<>();
        JSONArray phoneNumber = object.optJSONArray("phoneNumber");
        for (int i = 0; i < phoneNumber.length(); i++) {
            JSONObject numberObj = phoneNumber.optJSONObject(i);
            Phone phone = new Phone();
            phone.setType(numberObj.optString("type"));
            phone.setNumber(numberObj.optString("number"));
            phones.add(phone);
        }
        user.setPhoneNumber(phones);
        return user;
    }
}

（二）用fastjson去解析一个json字符串

用fastjson解析json字符串需要先导入jar包，在这里我推荐用maven去导入包，这样有一个好处，就是可以导入其依赖的相关jar包。

实体类如下图：

public class User {
    @JSONField(name = "firstName")//注意，属性加入此注解，则在java文件混淆后依然可以得到这个属性
    private String firstName;
    private String lastName;
    private String sex;
    private int age;
    @JSONField(serialize = false)//此注解可以使序列化后的json字符串中没有这个属性
    private Address address;
    private List<Phone> phoneNumber;
    @JSONField(name = "10000")
    private String text;
    private int x;
    private int y;

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }

    public List<Phone> getPhoneNumber() {
        return phoneNumber;
    }

    public void setPhoneNumber(List<Phone> phoneNumber) {
        this.phoneNumber = phoneNumber;
    }

    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }
    @JSONField(name = "location")
    public void setLocation(List<Integer> location) {
        x = location.get(0);
        y = location.get(1);
    }

    public int getX() {
        return x;
    }

    public int getY() {
        return y;
    }
}

public class Address {
    private String streetAddress;
    private String city;
    private String state;
    private String postalCode;

    public String getStreetAddress() {
        return streetAddress;
    }

    public void setStreetAddress(String streetAddress) {
        this.streetAddress = streetAddress;
    }

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }

    public String getPostalCode() {
        return postalCode;
    }

    public void setPostalCode(String postalCode) {
        this.postalCode = postalCode;
    }
}

public class Phone {
    private String type;
    private String number;

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public String getNumber() {
        return number;
    }

    public void setNumber(String number) {
        this.number = number;
    }
}

解析方式如下代码：

public class Test {
    public static void main(String[] args) {
        String src = "{\n" +
                "     \"firstName\": \"John\",\n" +
                "     \"10000\": \"一万\",\n" +
                "     \"location\": [50, 100],\n" +
                "     \"lastName\": \"Smith\",\n" +
                "     \"sex\": \"male\",\n" +
                "     \"age\": 25,\n" +
                "     \"address\": \n" +
                "     {\n" +
                "         \"streetAddress\": \"21 2nd Street\",\n" +
                "         \"city\": \"New York\",\n" +
                "         \"state\": \"NY\",\n" +
                "         \"postalCode\": \"10021\"\n" +
                "     },\n" +
                "     \"phoneNumber\": \n" +
                "     [\n" +
                "         {\n" +
                "           \"type\": \"home\",\n" +
                "           \"number\": \"212 555-1234\"\n" +
                "         },\n" +
                "         {\n" +
                "           \"type\": \"fax\",\n" +
                "           \"number\": \"646 555-4567\"\n" +
                "         }\n" +
                "     ]\n" +
                " }";
//        Map parse = (Map) JSON.parse(src);
//        System.out.println(((Map) parse.get("address")).get("streetAddress"));
//        System.out.println(((Map) ((List) parse.get("phoneNumber")).get(0)).get("type"));
        User user = JSON.parseObject(src, User.class);
        System.out.println(user.getFirstName());
//        System.out.println(user.getText());
//        System.out.println(user.getX());
//        System.out.println(user.getY());
        System.out.println(JSON.toJSONString(user));
//        List<Integer> list = JSON.parseArray("[100, 40, 12, 452]", Integer.class);
//        System.out.println(user.getAddress().getCity());
//        System.out.println(user.getPhoneNumber().get(0).getNumber());
    }
}