73 lines
1.7 KiB
Markdown
73 lines
1.7 KiB
Markdown
# Spring PropertyPlaceholderConfigurerResolver
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- 类全路径: `org.springframework.beans.factory.config.PropertyPlaceholderConfigurer.PropertyPlaceholderConfigurerResolver`
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- 这个类是从 Properties 中获取属性
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```java
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private final class PropertyPlaceholderConfigurerResolver implements PlaceholderResolver {
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private final Properties props;
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private PropertyPlaceholderConfigurerResolver(Properties props) {
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this.props = props;
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}
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@Override
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@Nullable
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public String resolvePlaceholder(String placeholderName) {
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return PropertyPlaceholderConfigurer.this.resolvePlaceholder(placeholderName,
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this.props, systemPropertiesMode);
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}
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}
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```
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- 详细方法如下
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```java
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@Nullable
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protected String resolvePlaceholder(String placeholder, Properties props, int systemPropertiesMode) {
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String propVal = null;
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if (systemPropertiesMode == SYSTEM_PROPERTIES_MODE_OVERRIDE) {
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propVal = resolveSystemProperty(placeholder);
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}
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if (propVal == null) {
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propVal = resolvePlaceholder(placeholder, props);
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}
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if (propVal == null && systemPropertiesMode == SYSTEM_PROPERTIES_MODE_FALLBACK) {
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propVal = resolveSystemProperty(placeholder);
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}
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return propVal;
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}
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```
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```java
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@Nullable
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protected String resolvePlaceholder(String placeholder, Properties props) {
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return props.getProperty(placeholder);
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}
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```
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```java
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@Nullable
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protected String resolveSystemProperty(String key) {
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try {
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String value = System.getProperty(key);
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if (value == null && this.searchSystemEnvironment) {
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value = System.getenv(key);
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}
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return value;
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}
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catch (Throwable ex) {
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if (logger.isDebugEnabled()) {
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logger.debug("Could not access system property '" + key + "': " + ex);
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}
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return null;
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}
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}
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```
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