JsonMappingException：找不到适合类型[简单类型，类]的构造函数：无法从JSON对象实例化

所以，最后我意识到了问题所在。我怀疑这不是杰克逊的配置问题。

实际上问题出在ApplesDO类中：

public class ApplesDO {    private String apple;    public String getApple() {        return apple;    }    public void setApple(String apple) {        this.apple = apple;    }    public ApplesDO(CustomType custom) {        //constructor Code    }}

为该类定义了一个自定义构造函数，使其成为默认构造函数。引入虚拟构造函数使错误消失了：

public class ApplesDO {    private String apple;    public String getApple() {        return apple;    }    public void setApple(String apple) {        this.apple = apple;    }    public ApplesDO(CustomType custom) {        //constructor Code    }    //Introducing the dummy constructor    public ApplesDO() {    }}