使用Spring实现属性文件给常量赋值

测试代码如下;

 

package com.yanek.ioc;import org.junit.Test;import org.junit.runner.RunWith;import org.springframework.test.context.ContextConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = { "classpath:spring-base.xml"})public class MyTest3 {@Testpublic void test() {System.out.println("CHARSET:"+com.yanek.util.ConfigConstants.CHARSET);System.out.println("CONNECTTIMEOUT:"+com.yanek.util.ConfigConstants.CONNECTTIMEOUT);System.out.println("READTIMEOUT:"+com.yanek.util.ConfigConstants.READTIMEOUT);}}

 

测试输出如下：

 

CHARSET:UTF-8
CONNECTTIMEOUT:1000
READTIMEOUT:5000

 

核心类：

package com.yanek.util;import java.lang.reflect.Field;import java.util.Enumeration;import java.util.Properties;import java.util.regex.Matcher;import java.util.regex.Pattern;import org.springframework.beans.BeansException;import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;/** * 自定义PropertyPlaceholderConfigurer返回properties内容 */ public class CustomizedPropertyPlaceholderConfigurer extends PropertyPlaceholderConfigurer {/** * 属性前缀，可以使用表达式${}。如果使用表达式，表示从属性文件中的字段读取。 * 如果为空，表示不使用前缀。 */private String prefix;/** * 需要注入的常量类名数组 */private String[] configureClasses;@SuppressWarnings("unchecked")protected void processProperties(ConfigurableListableBeanFactory beanFactoryToProcess, Properties props)throws BeansException {super.processProperties(beanFactoryToProcess, props);if (configureClasses == null) return;String prefixValue = null;if (prefix != null && !prefix.isEmpty()){// 如果前缀是表达式，需要从属性中读取Pattern p = Pattern.compile("\\$\\{(.*)\\}");Matcher matcher = p.matcher(prefix);prefixValue = prefix;if (matcher.find()) {String prefixKey = matcher.group(1);prefixValue = props.getProperty(prefixKey);}}// 遍历多个常量类for (int i = 0; i < configureClasses.length; i++) {Class c = null;try {c = Class.forName(configureClasses[i]);} catch (ClassNotFoundException e) {e.printStackTrace();continue;}Field[] fields = c.getFields();// 遍历属性列表，注入到常量字段中for (Enumeration<?> k = props.propertyNames(); k.hasMoreElements();) {String key = (String) k.nextElement();// 遍历常量字段数组，找到与属性对应的常量字段for (int j = 0; fields != null && j < fields.length; j++) {// 取出字段名称，如果有前缀，需要加上前缀String keyStr = fields[j].getName();if (prefixValue != null && !prefixValue.isEmpty())keyStr = prefixValue + "." + fields[j].getName();// 判断常量字段是否有属性匹配，不区分大小写。if (keyStr.equalsIgnoreCase(key)) {// 从属性中取出字段值，并存到字段中String value = props.getProperty(key);if (value != null) {value = value.trim();// fields[j].setAccessible(true);try {if (Integer.TYPE.equals(fields[j].getType())) {fields[j].setInt(null, Integer.parseInt(value));} else if (Long.TYPE.equals(fields[j].getType())) {fields[j].setLong(null, Long.parseLong(value));} else if (Short.TYPE.equals(fields[j].getType())) {fields[j].setShort(null, Short.parseShort(value));} else if (Double.TYPE.equals(fields[j].getType())) {fields[j].setDouble(null, Double.parseDouble(value));} else if (Float.TYPE.equals(fields[j].getType())) {fields[j].setFloat(null, Float.parseFloat(value));} else if (Boolean.TYPE.equals(fields[j].getType())) {fields[j].setBoolean(null, Boolean.parseBoolean(value));} else {fields[j].set(null, value);}} catch (IllegalArgumentException e) {e.printStackTrace();} catch (IllegalAccessException e) {e.printStackTrace();}}break;}}}}}public String getPrefix() {return prefix;}public void setPrefix(String prefix) {this.prefix = prefix;}public String[] getConfigureClasses() {return configureClasses;}public void setConfigureClasses(String[] configureClasses) {this.configureClasses = (configureClasses != null)? configureClasses.clone() : null;}public void setConfigureClass(String configureClass) {this.configureClasses = new String[] {configureClass};}}

 

package com.yanek.util;public class ConfigConstants {public static int CONNECTTIMEOUT = 0;public static int READTIMEOUT = 0;public static String CHARSET = "";}

属性文件：application.properties

CONNECTTIMEOUT=1000READTIMEOUT=5000CHARSET=UTF-8

 spring配置文件：

 

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:context="http://www.springframework.org/schema/context"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-2.5.xsdhttp://www.springframework.org/schema/context  http://www.springframework.org/schema/context/spring-context-2.5.xsd"default-autowire="byName" default-lazy-init="false"><!-- 从properties文件加载配置信息 --><bean id="propertyPlaceholderConfigurer"class="com.yanek.util.CustomizedPropertyPlaceholderConfigurer"><property name="locations"><list><value>classpath:application.properties</value></list></property><property name="configureClasses"><list><value>com.yanek.util.ConfigConstants</value></list></property></bean></beans>