如何使用傑克遜

Question

我有以下值String解析一個JSON字符串數組：

[{"key1":"value11", "key2":"value12"},{"key1":"value21", "key2":"value22"}] 

及以下等級：

public class SomeClass { 
    private String key1; 
    private String key2; 
    /* ... getters and setters omitted ...*/ 
} 

我想將它解析爲List<SomeClass>或SomeClass[]

哪一種最簡單的方法使用JacksonObjectMapper？

Answer 1

我終於明白了：

ObjectMapper objectMapper = new ObjectMapper(); 
TypeFactory typeFactory = objectMapper.getTypeFactory(); 
List<SomeClass> someClassList = objectMapper.readValue(jsonString, typeFactory.constructCollectionType(List.class, SomeClass.class)); 

Answer 2

對方回答是正確的，但爲了完整性，這裏有其他的方法：

List<SomeClass> list = mapper.readValue(jsonString, new TypeReference<List<SomeClass>>() { }); 
SomeClass[] array = mapper.readValue(jsonString, SomeClass[].class); 

Answer 3

完整的例子使用數組。 替換 「constructArrayType（）」，由 「constructCollectionType（）」 或其它任何你需要的類型。

import java.io.IOException; 

import com.fasterxml.jackson.core.JsonParseException; 
import com.fasterxml.jackson.databind.ObjectMapper; 
import com.fasterxml.jackson.databind.type.TypeFactory; 

public class Sorting { 

    private String property; 

    private String direction; 

    public Sorting() { 

    } 

    public Sorting(String property, String direction) { 
     this.property = property; 
     this.direction = direction; 
    } 

    public String getProperty() { 
     return property; 
    } 

    public void setProperty(String property) { 
     this.property = property; 
    } 

    public String getDirection() { 
     return direction; 
    } 

    public void setDirection(String direction) { 
     this.direction = direction; 
    } 

    public static void main(String[] args) throws JsonParseException, IOException { 
     final String json = "[{\"property\":\"title1\", \"direction\":\"ASC\"}, {\"property\":\"title2\", \"direction\":\"DESC\"}]"; 
     ObjectMapper mapper = new ObjectMapper(); 
     Sorting[] sortings = mapper.readValue(json, TypeFactory.defaultInstance().constructArrayType(Sorting.class)); 
     System.out.println(sortings); 
    } 
}