移除canal.instance.spring 依赖后，需要加入druid与mysql connector的依赖 2. PropertyPlaceholderConfigurer由canal.instance.spring移至db

example/src/main/java/com/alibaba/otter/canal/example/db/PropertyPlaceholderConfigurer.java

@@ -0,0 +1,169 @@
+package com.alibaba.otter.canal.example.db;
+
+import org.springframework.beans.factory.InitializingBean;
+import org.springframework.context.ResourceLoaderAware;
+import org.springframework.core.io.Resource;
+import org.springframework.core.io.ResourceLoader;
+import org.springframework.util.Assert;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Properties;
+
+/**
+ * 扩展Spring的
+ * {@linkplain org.springframework.beans.factory.config.PropertyPlaceholderConfigurer}
+ * ，增加默认值的功能。 例如：${placeholder:defaultValue}，假如placeholder的值不存在，则默认取得
+ * defaultValue。
+ * 
+ * @author jianghang 2013-1-24 下午03:37:56
+ * @version 1.0.0
+ */
+public class PropertyPlaceholderConfigurer extends org.springframework.beans.factory.config.PropertyPlaceholderConfigurer implements ResourceLoaderAware, InitializingBean {
+
+    private static final String PLACEHOLDER_PREFIX = "${";
+    private static final String PLACEHOLDER_SUFFIX = "}";
+    private ResourceLoader      loader;
+    private String[]            locationNames;
+
+    public PropertyPlaceholderConfigurer(){
+        setIgnoreUnresolvablePlaceholders(true);
+    }
+
+    public void setResourceLoader(ResourceLoader loader) {
+        this.loader = loader;
+    }
+
+    public void setLocationNames(String[] locations) {
+        this.locationNames = locations;
+    }
+
+    public void afterPropertiesSet() throws Exception {
+        Assert.notNull(loader, "no resourceLoader");
+
+        if (locationNames != null) {
+            for (int i = 0; i < locationNames.length; i++) {
+                locationNames[i] = resolveSystemPropertyPlaceholders(locationNames[i]);
+            }
+        }
+
+        if (locationNames != null) {
+            List<Resource> resources = new ArrayList<Resource>(locationNames.length);
+
+            for (String location : locationNames) {
+                location = trimToNull(location);
+
+                if (location != null) {
+                    resources.add(loader.getResource(location));
+                }
+            }
+
+            super.setLocations(resources.toArray(new Resource[resources.size()]));
+        }
+    }
+
+    private String resolveSystemPropertyPlaceholders(String text) {
+        StringBuilder buf = new StringBuilder(text);
+
+        for (int startIndex = buf.indexOf(PLACEHOLDER_PREFIX); startIndex >= 0;) {
+            int endIndex = buf.indexOf(PLACEHOLDER_SUFFIX, startIndex + PLACEHOLDER_PREFIX.length());
+
+            if (endIndex != -1) {
+                String placeholder = buf.substring(startIndex + PLACEHOLDER_PREFIX.length(), endIndex);
+                int nextIndex = endIndex + PLACEHOLDER_SUFFIX.length();
+
+                try {
+                    String value = resolveSystemPropertyPlaceholder(placeholder);
+
+                    if (value != null) {
+                        buf.replace(startIndex, endIndex + PLACEHOLDER_SUFFIX.length(), value);
+                        nextIndex = startIndex + value.length();
+                    } else {
+                        System.err.println("Could not resolve placeholder '"
+                                           + placeholder
+                                           + "' in ["
+                                           + text
+                                           + "] as system property: neither system property nor environment variable found");
+                    }
+                } catch (Throwable ex) {
+                    System.err.println("Could not resolve placeholder '" + placeholder + "' in [" + text
+                                       + "] as system property: " + ex);
+                }
+
+                startIndex = buf.indexOf(PLACEHOLDER_PREFIX, nextIndex);
+            } else {
+                startIndex = -1;
+            }
+        }
+
+        return buf.toString();
+    }
+
+    private String resolveSystemPropertyPlaceholder(String placeholder) {
+        DefaultablePlaceholder dp = new DefaultablePlaceholder(placeholder);
+        String value = System.getProperty(dp.placeholder);
+
+        if (value == null) {
+            value = System.getenv(dp.placeholder);
+        }
+
+        if (value == null) {
+            value = dp.defaultValue;
+        }
+
+        return value;
+    }
+
+    @Override
+    protected String resolvePlaceholder(String placeholder, Properties props, int systemPropertiesMode) {
+        DefaultablePlaceholder dp = new DefaultablePlaceholder(placeholder);
+        String value = super.resolvePlaceholder(dp.placeholder, props, systemPropertiesMode);
+
+        if (value == null) {
+            value = dp.defaultValue;
+        }
+
+        return trimToEmpty(value);
+    }
+
+    private static class DefaultablePlaceholder {
+
+        private final String defaultValue;
+        private final String placeholder;
+
+        public DefaultablePlaceholder(String placeholder){
+            int commaIndex = placeholder.indexOf(":");
+            String defaultValue = null;
+
+            if (commaIndex >= 0) {
+                defaultValue = trimToEmpty(placeholder.substring(commaIndex + 1));
+                placeholder = trimToEmpty(placeholder.substring(0, commaIndex));
+            }
+
+            this.placeholder = placeholder;
+            this.defaultValue = defaultValue;
+        }
+    }
+
+    private String trimToNull(String str) {
+        if (str == null) {
+            return null;
+        }
+
+        String result = str.trim();
+
+        if (result == null || result.length() == 0) {
+            return null;
+        }
+
+        return result;
+    }
+
+    public static String trimToEmpty(String str) {
+        if (str == null) {
+            return "";
+        }
+
+        return str.trim();
+    }
+}

example/src/main/resources/client-spring.xml

@@ -4,7 +4,7 @@
        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd"
        default-autowire="byName">
 
-    <bean class="com.alibaba.otter.canal.instance.spring.support.PropertyPlaceholderConfigurer" lazy-init="false">
+    <bean class="com.alibaba.otter.canal.example.db.PropertyPlaceholderConfigurer" lazy-init="false">
         <property name="ignoreResourceNotFound" value="true"/>
         <property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE"/><!-- 允许system覆盖 -->
         <property name="locationNames">