json字符串转对象bean

要将JSON字符串转换为Java对象，可以使用Jackson库。Jackson是一个流行的Java库，用于处理JSON数据。以下是使用Jackson将JSON字符串转换为Java对象的示例：

1.首先，需要将JSON字符串读入输入流中：

String jsonString = "{\"name\":\"John\",\"age\":30,\"city\":\"New York\"}";

ObjectMapper objectMapper = new ObjectMapper();
InputStream inputStream = new ByteArrayInputStream(jsonString.getBytes());

2.然后，使用ObjectMapper类的readValue方法将JSON字符串转换为Java对象：

Person person = objectMapper.readValue(inputStream, Person.class);

在这个例子中，Person是一个Java类，它的属性与JSON字符串中的字段相匹配。

完整示例代码：

import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;

public class JsonToObjectDemo {
    public static void main(String[] args) throws IOException {
        String jsonString = "{\"name\":\"John\",\"age\":30,\"city\":\"New York\"}";

        ObjectMapper objectMapper = new ObjectMapper();
        InputStream inputStream = new ByteArrayInputStream(jsonString.getBytes());

        Person person = objectMapper.readValue(inputStream, Person.class);
        System.out.println(person.getName());
        System.out.println(person.getAge());
        System.out.println(person.getCity());
    }
}

class Person {
    private String name;
    private int age;
    private String city;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

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

    public String getCity() {
        return city;
    }

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

输出：

John
30
New York