https://index.zshipu.com/geek/tags/PlaceholderResolver/ Recent content in PlaceholderResolver on 知识铺的博客 Hugo -- gohugo.io zh-CN Wed, 06 Mar 2024 12:35:00 +0000 https://index.zshipu.com/geek/post/code/docs/Spring/clazz/PlaceholderResolver/Spring-SystemPropertyPlaceholderResolver/ Wed, 06 Mar 2024 12:35:00 +0000 https://index.zshipu.com/geek/post/code/docs/Spring/clazz/PlaceholderResolver/Spring-SystemPropertyPlaceholderResolver/ Spring SystemPropertyPlaceholderResolver 类全路径: org.springframework.util.SystemPropertyUtils.SystemPropertyPlaceholderResolver 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 private static class SystemPropertyPlaceholderResolver implements PropertyPlaceholderHelper.PlaceholderResolver { private final String text; public SystemPropertyPlaceholderResolver(String text) { this.text = text; } @Override @Nullable public String resolvePlaceholder(String placeholderName) { try { String propVal = System.getProperty(placeholderName); if (propVal == null) { // Fall back to searching the system environment. // 获取系统属性 propVal = System.getenv(placeholderName); } return propVal; } catch (Throwable ex) { System.err.println("Could not resolve placeholder '" + placeholderName + "' in [" + this.text + "] as system property: " + ex); return null; } } } https://index.zshipu.com/geek/post/code/docs/Spring/clazz/PlaceholderResolver/Spring-ServletContextPlaceholderResolver/ Wed, 06 Mar 2024 12:34:00 +0000 https://index.zshipu.com/geek/post/code/docs/Spring/clazz/PlaceholderResolver/Spring-ServletContextPlaceholderResolver/ Spring ServletContextPlaceholderResolver 类全路径: org.springframework.web.util.ServletContextPropertyUtils.ServletContextPlaceholderResolver 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 private static class ServletContextPlaceholderResolver implements PropertyPlaceholderHelper.PlaceholderResolver { private final String text; private final ServletContext servletContext; public ServletContextPlaceholderResolver(String text, ServletContext servletContext) { this.text = text; this.servletContext = servletContext; } @Override @Nullable public String resolvePlaceholder(String placeholderName) { try { // servlet 上下文获取 String propVal = this.servletContext.getInitParameter(placeholderName); if (propVal == null) { // Fall back to system properties. propVal = System.getProperty(placeholderName); if (propVal == null) { // Fall back to searching the system environment. propVal = System.getenv(placeholderName); } } return propVal; } catch (Throwable ex) { System.err.println("Could not resolve placeholder '" + placeholderName + "' in https://index.zshipu.com/geek/post/code/docs/Spring/clazz/PlaceholderResolver/Spring-PropertyPlaceholderConfigurerResolver/ Wed, 06 Mar 2024 12:33:00 +0000 https://index.zshipu.com/geek/post/code/docs/Spring/clazz/PlaceholderResolver/Spring-PropertyPlaceholderConfigurerResolver/ Spring PropertyPlaceholderConfigurerResolver 类全路径: org.springframework.beans.factory.config.PropertyPlaceholderConfigurer.PropertyPlaceholderConfigurerResolver 这个类是从 Properties 中获取属性 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 private final class PropertyPlaceholderConfigurerResolver implements PlaceholderResolver { private final Properties props; private PropertyPlaceholderConfigurerResolver(Properties props) { this.props = props; } @Override @Nullable public String resolvePlaceholder(String placeholderName) { return PropertyPlaceholderConfigurer.this.resolvePlaceholder(placeholderName, this.props, systemPropertiesMode); } } 详细方法如下 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 @Nullable protected String resolvePlaceholder(String placeholder, Properties props, int systemPropertiesMode) { String propVal = null; if (systemPropertiesMode == SYSTEM_PROPERTIES_MODE_OVERRIDE) { propVal = resolveSystemProperty(placeholder); } if (propVal == null) { propVal = resolvePlaceholder(placeholder, props); } if (propVal == null && systemPropertiesMode == SYSTEM_PROPERTIES_MODE_FALLBACK) { propVal = resolveSystemProperty(placeholder); } return propVal; } 1 2 3 4 https://index.zshipu.com/geek/post/code/docs/Spring/clazz/PlaceholderResolver/Spring-PlaceholderResolver/ Wed, 06 Mar 2024 12:32:00 +0000 https://index.zshipu.com/geek/post/code/docs/Spring/clazz/PlaceholderResolver/Spring-PlaceholderResolver/ Spring PlaceholderResolver 类全路径: org.springframework.util.PropertyPlaceholderHelper.PlaceholderResolver 类作用将占位符中的内容替换成属性值. 假设现有属性表: user.dir = c:\home 传入参数 user.dir 会获得 c:\home 1 2 3 4 5 6 7 8 9 10 11 12 @FunctionalInterface public interface PlaceholderResolver { /** * Resolve the supplied placeholder name to the replacement value. * @param placeholderName the name of the placeholder to resolve * @return the replacement value, or {@code null} if no replacement is to be made */ @Nullable String resolvePlaceholder(String placeholderName); } 类图如下