java - 在java中从字符串中读取json

Question

如果JSON数据在字符串中，如何从下面的JSON中读取数据

{
    "name": "test",
    "values": [
        {
            "valu": "23",
            "valu1": "24",
            "valu2": "25"
        }
    ]
}

Answer 1

使用 Gson和 Gson#fromJson 方法之一

fromJson(String, Class)

YourType o = new Gson().fromJson("your json string", YourType.class);

fromJson(Reader, Class)

YourType o = new Gson().fromJson(new StringReader("your json string"), 
    YourType.class);

简单的例子:

定义要将 json 数据映射到的类:

static class Hobby {
    Hobby(String n) { name = n; }
    String name;
    @Override
    public String toString() {
        return "Hobby [name=" + name + "]";
    }
}

static class Person {
    String firstName, lastName;
    int age;
    List<Hobby> hobbies = new ArrayList<Hobby>();
    @Override
    public String toString() {
        return "Person [firstName=" + firstName + ", lastName=" + lastName
                + ", age=" + age + ", hobbies=" + hobbies + "]";
    } 
}

现在使用以下 Json 字符串进行测试

@Test
public void fromJson() {
    Person o = new Gson().fromJson(
            "{\r\n" + 
            "    \"firstName\":\"John\",\r\n" + 
            "    \"lastName\":\"Doe\",\r\n" + 
            "    \"age\":24,\r\n" + 
            "    \"hobbies\":[\r\n" + 
            "        {\r\n" + 
            "            \"name\":\"Programming\"\r\n" + 
            "        },\r\n" + 
            "        {\r\n" + 
            "            \"name\":\"Sports\"\r\n" + 
            "        }\r\n" + 
            "   ]\r\n" + 
            "}",
            Person.class);
    System.out.println(o.toString());
}

这打印:

Person [firstName=John, lastName=Doe, age=24, hobbies=[Hobby [name=Programming], Hobby [name=Sports]]]

查看类的javadoc Gson对于其他选择。也看看他们的 user-guide