ModelMapper：如何映射java.util.Map到POJO？

Question

如何映射java.util.Map到POJO？

以下測試給我一個配置錯誤。

似乎有一個類似的問題被打開，但沒有解決https://github.com/jhalterman/modelmapper/issues/116。

測試：

package org.me.modelmapper; 

import java.util.HashMap; 
import org.modelmapper.ModelMapper; 
import org.modelmapper.PropertyMap; 
import org.testng.Assert; 
import org.testng.annotations.BeforeMethod; 
import org.testng.annotations.Test; 

public class MapperTest { 


    private ModelMapper modelMapper; 


    public MapperTest() { 
    } 


    public static class Foo { 

     public String a; 
     public String b; 

     public String getA() { 
      return a; 
     } 

     public void setA(String a) { 
      this.a = a; 
     } 

     public String getB() { 
      return b; 
     } 

     public void setB(String b) { 
      this.b = b; 
     } 

    } 


    @BeforeMethod 
    public void setUpMethod() throws Exception { 
     modelMapper = new ModelMapper(); 
     modelMapper.getConfiguration() 
       .setFieldMatchingEnabled(true); 
    } 

    @Test 
    public void shouldMapHashMapToFoo() { 
     HashMap<String, String> map = new HashMap<>(); 
     map.put("a", "aaaa"); 
     map.put("b", "bbbb"); 

     PropertyMap<HashMap<String, String>, Foo> fooMap = new PropertyMap<HashMap<String, String>, MapperTest.Foo>() { 

      @Override 
      protected void configure() { 
       map(source.get("a"), destination.a); 
       map(source.get("b"), destination.b); 
      } 

     }; 

     modelMapper.addMappings(fooMap); 

     Foo foo = modelMapper.map(map, Foo.class); 

     Assert.assertEquals(foo.getA(), map.get("a")); 
     Assert.assertEquals(foo.getB(), map.get("b")); 

    } 

} 

錯誤：

Configuring TestNG with: org.apache.maven.surefire.testng.conf.TestNG652Configurator@60acc399 
Tests run: 1, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 2.326 sec <<< FAILURE! 
shouldMapHashMapToFoo(org.me.modelmapper.MapperTest) Time elapsed: 0.186 sec <<< FAILURE! 
org.modelmapper.ConfigurationException: ModelMapper configuration errors: 

1) Invalid source method java.util.HashMap.get(). Ensure that method has zero parameters and does not return void. 

2) Invalid source method java.util.HashMap.get(). Ensure that method has zero parameters and does not return void. 

2 errors 
    at org.modelmapper.internal.Errors.throwConfigurationExceptionIfErrorsExist(Errors.java:241) 
    at org.modelmapper.internal.ExplicitMappingBuilder.visitPropertyMap(ExplicitMappingBuilder.java:228) 
    at org.modelmapper.PropertyMap.configure(PropertyMap.java:380) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:606) 
    at org.modelmapper.internal.ExplicitMappingBuilder.build(ExplicitMappingBuilder.java:194) 
    at org.modelmapper.internal.TypeMapImpl.addMappings(TypeMapImpl.java:72) 
    at org.modelmapper.internal.TypeMapStore.getOrCreate(TypeMapStore.java:101) 
    at org.modelmapper.ModelMapper.addMappings(ModelMapper.java:93) 
    at org.me.modelmapper.MapperTest.shouldMapHashMapToFoo(MapperTest.java:354) 


Results : 

Failed tests: shouldMapHashMapToFoo(org.me.modelmapper.MapperTest): ModelMapper configuration errors: 
(..) 

Tests run: 1, Failures: 1, Errors: 0, Skipped: 0 

Answer 1

它會自動映射。你不需要需要配置任何映射。這將工作：

@Test 
public void shouldMapHashMapToFoo() { 
    HashMap<String, String> map = new HashMap<>(); 
    map.put("a", "aaaa"); 
    map.put("b", "bbbb"); 

    Foo foo = modelMapper.map(map, Foo.class); 

    Assert.assertEquals(foo.getA(), map.get("a")); 
    Assert.assertEquals(foo.getB(), map.get("b")); 

} 

編輯： 如果您需要映射的HashMap更復雜的結構，你可以隨時使用「中間」級。

public static class Bar 
    { 
    private String Z; 
    private String W; 

    public String getZ() 
    { 
     return Z; 
    } 

    public void setZ(String z) 
    { 
     Z = z; 
    } 

    public String getW() 
    { 
     return W; 
    } 

    public void setW(String w) 
    { 
     W = w; 
    } 
    } 

    @Test 
    public void shouldMapHashMapToFoo() 
    { 
    HashMap<String, String> map = new HashMap<>(); 
    map.put("z", "aaaa"); 
    map.put("w", "bbbb"); 

    Bar bar = modelMapper.map(map, Bar.class); 

    PropertyMap<Bar, Foo> barToFooMap = new PropertyMap<Bar, Foo>() 
    { 
     @Override 
     protected void configure() 
     { 
     map().setA(source.getZ()); 
     map().setB(source.getW()); 
     } 

    }; 
    modelMapper.addMappings(barToFooMap); 

    Foo foo = modelMapper.map(bar, Foo.class); 

    Assert.assertEquals(foo.getA(), map.get("z")); 
    Assert.assertEquals(foo.getB(), map.get("w")); 
    }