使用泛型，设计统一返回工具类

规定统一返回格式

/**
 * 自定义泛型类
 */
public class ReturnResult<T> {

    //返回码
    private String returnCode;

    //返回说明
    private String returnMsg;

    //返回数据
    private T returnData;

    public String getReturnCode() {
        return returnCode;
    }

    public void setReturnCode(String returnCode) {
        this.returnCode = returnCode;
    }

    public String getReturnMsg() {
        return returnMsg;
    }

    public void setReturnMsg(String returnMsg) {
        this.returnMsg = returnMsg;
    }

    public T getReturnData() {
        return returnData;
    }

    public void setReturnData(T returnData) {
        this.returnData = returnData;
    }

    @Override
    public String toString() {
        return "ReturnResult{" +
                "returnCode='" + returnCode + '\'' +
                ", returnMsg='" + returnMsg + '\'' +
                ", returnData=" + returnData +
                '}';
    }
}

定义工具类

/**
 * 统一返回工具类
 */
public class ReturnUtil {
    /**
     *
     * 请求返回成功工具类
     *
     */
    public static <T> ReturnResult<T> success(T t){
        ReturnResult<T> returnResult = new ReturnResult<T>();
        returnResult.setReturnCode("0000");
        returnResult.setReturnMsg("success");
        returnResult.setReturnData(t);
        return returnResult;
    }
    public static void main(String args[]){
        List<Car> list = new ArrayList<Car>();
        list.add(new Car("奥迪","A4",3000));
        list.add(new Car("奥迪","A6",3600));
        list.add(new Car("奥迪","A8",4000));
        System.out.println(success(list));
    }
}

测试实体类Car

public class Car {

    private String name;
    private String type;
    private int price;

    public Car() {
    }

    public Car(String name, String type, int price) {
        this.name = name;
        this.type = type;
        this.price = price;
    }

    public String getName() {
        return name;
    }

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

    public String getType() {
        return type;
    }

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

    public int getPrice() {
        return price;
    }

    public void setPrice(int price) {
        this.price = price;
    }

    @Override
    public String toString() {
        return "Car{" +
                "name='" + name + '\'' +
                ", type='" + type + '\'' +
                ", price=" + price +
                '}';
    }
}

输出结果

声明T，解决方法里的T不报错