[Java] MapStruct处理Java中实体与模型间不匹配属性转换的方法

public class user {
  private integer id;
  private string name;
  private double account;
  private boolean married;
// setters, getters, tostring()
}

public class employee {
  private int id;
  private string ename;
  private string position;
  private string married;
// setters, getters, tostring()
}

• 需要user 与employee 对象之间转换。
  
• user 的name属性对应employee 的ename属性，其取值相同，类型相同，名称不同
  
• user 的married属性(取值true和false)对应employee 的married属性(取值y和n)，其取值不同，类型不同，名称相同。
  

@mapper
public interface usermapper {
  usermapper instance = mappers.getmapper(usermapper.class);
  employee usertoemployee(user user);
  user employeetouser(employee employee);
}

@mapper
public interface usermapper {
  usermapper instance = mappers.getmapper(usermapper.class);
  @mappings({
  @mapping(source="name", target="ename")
  })
  employee usertoemployee(user user);
  @mappings({
  @mapping(source="ename", target="name")
  })
  user employeetouser(employee employee);
}

public class usertransform {
  public string booleantostring(boolean value){
  if(value){
    return "y";
  }
  return "n";
  }
  public boolean strtoboolean(string str){
  if ("y".equals(str)) {
    return true;
  }
  return false;
  }
}

@mapper(uses = usertransform.class)
public interface usermapper {...}

public class midtest {
  @test
  public void midtest(){
  user user = new user();
  user.setid(125);
  user.setname("lee");
  user.setmarried(true);
  employee e = usermapper.instance.usertoemployee(user);
  system.out.println(e);
  }
  @test
  public void midtest2(){
  employee e = new employee();
  e.setid(222);
  e.setename("chao");
  e.setmarried("n");
  user u = usermapper.instance.employeetouser(e);
  system.out.println(u);
  }
}

user [id=222, name=chao, account=0.0, married=false]
employee [id=125, ename=lee, position=null, married=y]

转换结果符合预期，转化期间不存在的属性，有了默认值(account和position)，包装类也能识别(int和integer)，从自动生成的usermapperimpl.java中，可以看到，
employee.setmarried( usertransform.booleantostring( user.ismarried() ) );，用到了刚才自定义的转换逻辑。第三种需求是很少的，但是遇到了也是很难解决的，mapstruct的自定义函数确实方便不少，不过与其他的转换工具相比，上手难度确实大，配置也稍显繁琐。