ModelMapper:如何将java.util.map映射到POJO

Question

如何将java.util.map映射到POJO？

下面的测试给了我一个配置错误。

类似的问题似乎已经解决，但没有得到解决https://github.com/jhalterman/modelmapper/issues/116.

测试：

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"));
    }
}

错误：

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

它是自动映射的。不需要配置任何映射。这将起作用：

@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"));
}

编辑：如果您需要将HashMap映射到更复杂的结构，您可以始终使用"中间"类。

  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"));
  }

Answer 2

注意，当从地图映射到对象时，忽略单词的大小写，例如：

map.put("test","0") & map.put("teSt","0") will work