JPA 配置类实体映射示例

A: 两张表示例

/** * * @author [e-mail] */@Entity@Table(name="apo_config")public class SiteConfig implements Serializable {    @Id    @GeneratedValue(strategy = GenerationType.IDENTITY)    private Long ID;    private String caption;    @ElementCollection(fetch = FetchType.LAZY)    @MapKeyColumn(name="name")    @Column(name="value")    @CollectionTable(name="apo_config_attributes", joinColumns=@JoinColumn(name="ca_id"))    private Map<String, String> attributes = new HashMap<String, String>();     //GET/SET}

测试代码

    @Test    public void test(){        SiteConfig sc=new SiteConfig();        sc.setID(1L);        sc.setCaption("全局配置");        Map<String, String> data=new HashMap<>();        data.put("site", "csdn.net");        data.put("account", "xiaofanku");        sc.setAttributes(data);        siteConfigDao.save(sc);    }    @Test    public void getConfig(){        SiteConfig config=siteConfigDao.findOne(1L);        assertEquals(config.getAttributes().get("site"), "csdn.net");    }

apo_config:表结构

apo_config_attributes:表结构

B: 三张表示例

/** *  * @author [e-mail] */@Entity@Table(name="apo_config")public class SiteConfig implements Serializable {    @Id    @GeneratedValue(strategy = GenerationType.IDENTITY)    private Long ID;    private String caption;    @OneToMany(cascade=CascadeType.ALL, orphanRemoval = true)    @MapKey(name="name")    @JoinTable(name = "apo_config_attributes")    private Map<String, ConfigAttribute> attributes=new HashMap<>();    //GET/SET}

/** * * @author [e-mail] */@Entity@Table(name="apo_attributes")public class ConfigAttribute implements Serializable {    @Id    @GeneratedValue(strategy = GenerationType.IDENTITY)    private Long ID;    @Column(name="name")    private String name;    private String value;    //GET/SET}

测试代码

    @Test @Ignore    public void test(){        SiteConfig sc=new SiteConfig();        sc.setID(1L);        sc.setCaption("全局配置");        Map<String, ConfigAttribute> data=new HashMap<>();        ConfigAttribute ca1=new ConfigAttribute();        ca1.setName("site");ca1.setValue("csdn.net");        data.put("site", ca1);        ConfigAttribute ca2=new ConfigAttribute();        ca2.setName("account");ca2.setValue("xiaofanku");        data.put("account", ca2);        sc.setAttributes(data);        siteConfigDao.save(sc);    }    @Test @Ignore    public void getConfig(){        SiteConfig config=siteConfigDao.findOne(1L);        assertEquals(config.getAttributes().get("site").getValue(), "csdn.net");    }

apo_config:表结构

apo_attributes:表结构

apo_config_attributes：中间表结构

C: 使用ASF Commons BeanUtils来构造一个Dynamic Class

import java.util.ArrayList;import java.util.List;import java.util.Map;import java.util.Objects;import java.util.Set;import org.apache.commons.beanutils.BasicDynaClass;import org.apache.commons.beanutils.ConvertUtils;import org.apache.commons.beanutils.DynaBean;import org.apache.commons.beanutils.DynaProperty;/** * 使用Commons Beanutils实现动态类 * @author [e-mail] * @since 20171024 */public class DynamicClass{    private final DynaBean config;    /**     * 构造一个运态类型     * @param attributeMeta key属性名,value为属性名的类型,例:java.lang.Boolean     * @throws IllegalAccessException     * @throws InstantiationException     * @throws ClassNotFoundException      */    public DynamicClass(Map<String,String> attributeMeta) throws IllegalAccessException, InstantiationException, ClassNotFoundException{        DynaProperty[] props=covert(attributeMeta).toArray(new DynaProperty[]{});        BasicDynaClass dynaClass = new BasicDynaClass("CustomConfig", null, props);        this.config = dynaClass.newInstance();    }    /**     * 构造一个运态类型     * @param attributes     * @throws ClassNotFoundException     * @throws IllegalAccessException     * @throws InstantiationException      */    public DynamicClass(Set<Attribute> attributes) throws ClassNotFoundException, IllegalAccessException, InstantiationException{        DynaProperty[] props=covert(attributes).toArray(new DynaProperty[]{});        BasicDynaClass dynaClass = new BasicDynaClass("CustomConfig", null, props);        this.config = dynaClass.newInstance();        load(attributes);    }    /**     * 获得属性值     * @param attributeName 属性名     * @return     */    public Object getValue(String attributeName){        return config.get(attributeName);    }    /**     * 获得属性值     * @param attributeName 属性名     * @param classType 属性类型     * @param <T>     * @return     * @throws java.lang.ClassCastException     */    public <T> T getValue(String attributeName, Class<T> classType) throws java.lang.ClassCastException{        return (T)getValue(attributeName);    }    /**     * 设置属性     * @param attributeName 属性名     * @param attributeValue 属性值     */    public void setValue(String attributeName, String attributeValue){        DynaProperty dp = config.getDynaClass().getDynaProperty(attributeName);        config.set(attributeName, ConvertUtils.convert(attributeValue, dp.getType()));    }    /**     * 设置属性     * @param attribute 属性实例     * @throws ClassNotFoundException     */    public void setValue(Attribute attribute) throws ClassNotFoundException {        config.set(attribute.getName(), ConvertUtils.convert(attribute.getValue(), Class.forName(attribute.getClassName())));    }    /**     * 装载属性集合,填充动态类实例     * @param attributes      */    private void load(Set<Attribute> attributes){        for(Attribute attr : attributes){            try{                config.set(attr.getName(), ConvertUtils.convert(attr.getValue(), Class.forName(attr.getClassName())));            }catch(ClassNotFoundException e){            }        }    }    /**     * 返回一个DynaProperty列表     * @param attributes     * @return     * @throws ClassNotFoundException     */    private List<DynaProperty> covert(Set<Attribute> attributes) throws ClassNotFoundException{        List<DynaProperty> attres=new ArrayList<>();        for(Attribute attr : attributes){            attres.add(new DynaProperty(attr.getName(), Class.forName(attr.getClassName())));        }        return attres;    }    /**     * 返回一个DynaProperty列表     * @param attributeMeta key属性名,value为属性名的类型,例:java.lang.Boolean     * @return     * @throws ClassNotFoundException     */    private List<DynaProperty> covert(Map<String,String> attributeMeta) throws ClassNotFoundException{        List<DynaProperty> properties=new ArrayList<>();        Set<String> attrSet=attributeMeta.keySet();        for(String attrName : attrSet){            String className=attributeMeta.get(attrName);            properties.add(new DynaProperty(attrName, Class.forName(className)));        }        return properties;    }    public static enum Type{        BOOLEAN("java.lang.Boolean"),        INTEGER("java.lang.Integer"),        LONG("java.lang.Long"),        STRING("java.lang.String"),        CHAR("java.lang.Character"),        DOUBLE("java.lang.Double"),        FLOAT("java.lang.Float");        private final String name;        private Type(String className){            this.name=className;        }        public String getName() {            return name;        }    }    public static class Attribute{        //属性名,例:show        private final String name;        //属性名的值,例:"true"        private final String value;        //属性名的类型,例:java.lang.Boolean        private final String className;        public Attribute(String name, String value, String className) {            this.name = name;            this.value = value;            this.className = className;        }        public String getName() {            return name;        }        public String getValue() {            return value;        }        public String getClassName() {            return className;        }        @Override        public int hashCode() {            int hash = 5;            hash = 97 * hash + Objects.hashCode(this.name);            hash = 97 * hash + Objects.hashCode(this.className);            return hash;        }        @Override        public boolean equals(Object obj) {            if (this == obj) {                return true;            }            if (obj == null) {                return false;            }            if (getClass() != obj.getClass()) {                return false;            }            final Attribute other = (Attribute) obj;            if (!Objects.equals(this.name, other.name)) {                return false;            }            if (!Objects.equals(this.className, other.className)) {                return false;            }            return true;        }    }}

测试代码:

    @Test    public void test(){        Set<Attribute> sas=new HashSet<>();        sas.add(new Attribute("logo", "logo.png", DynamicClass.Type.STRING.getName()));        sas.add(new Attribute("pageSize", "50", DynamicClass.Type.INTEGER.getName()));        sas.add(new Attribute("shortcut", "true", DynamicClass.Type.BOOLEAN.getName()));        try{            DynamicClass dc=new DynamicClass(sas);            Integer ps = dc.getValue("pageSize", Integer.class);            System.out.println(ps);            dc.setValue("pageSize", "150");            System.out.println(dc.getValue("pageSize"));        }catch(Exception e){            e.printStackTrace();        }    }    @Test @Ignore    public void base() {        Map<String, String> am = new HashMap<>();        am.put("logo", DynamicClass.Type.STRING.getName());        am.put("pageSize", DynamicClass.Type.INTEGER.getName());        am.put("shortcut", DynamicClass.Type.BOOLEAN.getName());        try {            DynamicClass dc = new DynamicClass(am);            dc.setValue("pageSize", "150");            System.out.println(dc.getValue("pageSize"));            dc.setValue(new Attribute("shortcut", "true", DynamicClass.Type.BOOLEAN.getName()));            System.out.println(dc.getValue("shortcut"));        } catch (IllegalAccessException | InstantiationException | ClassNotFoundException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }

最后说明:

JPA 2.1 实现 EclipseLink 2.5.2
JDK 1.8.x
Mysql 5.5.x
ASF Commons BeanUtils 1.8.3