如何从JavaBean(域类)的属性文件中读取值? [英] How to read values from property file in a JavaBean (domain class)?

问题描述

我有一个域类，我想从属性文件中读取值(自动装配messageSource在这里不起作用)，所以有什么想法吗? 我正在使用春天，冬眠 这是一个示例:

I have a domain class and I want to read values from property file (autowiring messageSource wouldn't work here) so any ideas ? I am using spring,hibernate and here's a sample:

package com.myapp.domain;

import java.io.Serializable;

import javax.persistence.Basic;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;


@SuppressWarnings("serial")
@Entity
@Table(name = "domain")
public class MyDomain implements Serializable {

    private long entityId;
    private String domain="some_hardcoded_value" // need to read it from a property file;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", unique = true, nullable = false)
    @Basic(fetch = FetchType.EAGER)
    public long getEntityId() {
        return entityId;
    }

    public void setEntityId(long entityId) {
        this.entityId = entityId;
    }

    public void setDomain(String domain) {
        this.domain = domain;
    }

    @Column(name = "domain")
    public String getDomain() {
        return domain;
    }

}

推荐答案

我仍然不明白这个问题，但是我假设您想从属性文件中设置bean属性.

I still don't understand the question, but I'll assume that you want to set bean properties from a properties file.

其他答案显示了如何从.properties文件中获取Properties对象(我将在下面显示其他方式)，我将向您展示如何使用Spring的BeanWrapper接口从其连接属性:

The other answers have shown how to get a Properties object from a .properties file (I'll show additional ways below), I will show you how to wire properties from it using Spring's BeanWrapper interface:

public static void wireBeanFromProperties(Object bean, Properties props){

    BeanWrapper wrapper = new BeanWrapperImpl(bean);
    for(Entry<Object, Object> entry:props.entrySet()){
        String propertyName = entry.getKey().toString();
        if(wrapper.isWritableProperty(propertyName)){
            wrapper.setPropertyValue(propertyName, entry.getValue());
        }
    }

}

或者，如果您确定可以将属性文件中的所有属性都映射到该类的bean属性，则:

Or, if you know for sure that all properties from the properties file can be mapped to this bean properties of the class:

public static void wireBeanFromProperties(final Object bean,
    final Properties props){
    final BeanWrapper wrapper = new BeanWrapperImpl(bean);
    // will throw an exception if the Properties object
    // contains any unknown keys
    wrapper.setPropertyValues(props);
}

参考:

Reference: 5.4. Bean manipulation and the BeanWrapper

实际上，从类路径加载资源的特定于Spring的方法使用

Actually, the Spring-specific ways to load resources from the classpath use the Resource mechanism

InputStream str = new ClassPathResource("classpath:some.properties")
                      .getInputStream();

令人高兴的是，您可以使用classpath:语法轻松地从XML连接InputStreams和资源:

The nice part is that you can wire both InputStreams and Resources easily from XML using the classpath: syntax:

Java代码

private InputStream stream;
private Resource resource;
public void setStream(InputStream stream){
    this.stream = stream;
}
public void setResource(Resource resource){
    this.resource = resource;
}

属性接线:

<bean class="MyClass">
    <property name="stream" value="classpath:file1.properties" />
    <property name="resource" value="classpath:file2.properties" />
</bean>

---

如果您只想初始化静态的final字段，请按以下步骤操作:

---

If you just want to initialize a static final field, here's how to do it:

private static final String DOMAIN;
static{
    InputStream inputStream=null;
    try{
        inputStream = new ClassPathResource("classpath:some.properties")
                          .getInputStream();
        Properties props = new Properties();
        props.load(inputStream);
        String key = "your.property";
        if(!props.containsKey(key))
            throw new IllegalStateException("Property not found");
        DOMAIN= props.getProperty(key);
    } catch(IOException e){
        throw new IllegalStateException(e);
    }finally{
        // apache commons / IO
        IOUtils.closeQuietly(inputStream);
    }
}

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