1. CommandInterceptor拦截器接口定义
package org.activiti.engine.impl.interceptor;
/**
* @author Tom Baeyens
*/
public interface CommandInterceptor {
<T> T execute(CommandConfig config, Command<T> command);
CommandInterceptor getNext();
void setNext(CommandInterceptor next);
}
2.commandExecutor命令执行器接口实现
package org.activiti.engine.impl.interceptor;
/**
* The command executor for internal usage.
*
* @author Tom Baeyens
*/
public interface CommandExecutor {
/**
* @return the default {@link CommandConfig}, used if none is provided.
*/
CommandConfig getDefaultConfig();
/**
* Execute a command with the specified {@link CommandConfig}.
*/
<T> T execute(CommandConfig config, Command<T> command);
/**
* Execute a command with the default {@link CommandConfig}.
*/
<T> T execute(Command<T> command);
}
3. CommandInterceptor抽象类接口实现
package org.activiti.engine.impl.interceptor;
/**
* @author Tom Baeyens
*/
public abstract class AbstractCommandInterceptor implements CommandInterceptor {
/**
* will be initialized by the {@link org.activiti.engine.ProcessEngineConfiguration ProcessEngineConfiguration}
*/
protected CommandInterceptor next;
@Override
public CommandInterceptor getNext() {
return next;
}
@Override
public void setNext(CommandInterceptor next) {
this.next = next;
}
}
4. 命令拦截器实现
package org.activiti.engine.impl.interceptor;
import org.activiti.engine.impl.cfg.ProcessEngineConfigurationImpl;
import org.activiti.engine.impl.context.Context;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* @author Tom Baeyens
* @author Joram Barrez
*/
public class CommandContextInterceptor extends AbstractCommandInterceptor {
private static final Logger log = LoggerFactory.getLogger(CommandContextInterceptor.class);
protected CommandContextFactory commandContextFactory;
protected ProcessEngineConfigurationImpl processEngineConfiguration;
public CommandContextInterceptor() {
}
public CommandContextInterceptor(CommandContextFactory commandContextFactory, ProcessEngineConfigurationImpl processEngineConfiguration) {
this.commandContextFactory = commandContextFactory;
this.processEngineConfiguration = processEngineConfiguration;
}
public <T> T execute(CommandConfig config, Command<T> command) {
CommandContext context = Context.getCommandContext();
boolean contextReused = false;
// We need to check the exception, because the transaction can be in a
// rollback state, and some other command is being fired to compensate (eg. decrementing job retries)
if (!config.isContextReusePossible() || context == null || context.getException() != null) {
context = commandContextFactory.createCommandContext(command);
} else {
log.debug("Valid context found. Reusing it for the current command '{}'", command.getClass().getCanonicalName());
contextReused = true;
context.setReused(true);
}
try {
// Push on stack
Context.setCommandContext(context);
Context.setProcessEngineConfiguration(processEngineConfiguration);
if (processEngineConfiguration.getActiviti5CompatibilityHandler() != null) {
Context.setActiviti5CompatibilityHandler(processEngineConfiguration.getActiviti5CompatibilityHandler());
}
return next.execute(config, command);
} catch (Throwable e) {
context.exception(e);
} finally {
try {
if (!contextReused) {
context.close();
}
} finally {
// Pop from stack
Context.removeCommandContext();
Context.removeProcessEngineConfiguration();
Context.removeBpmnOverrideContext();
Context.removeActiviti5CompatibilityHandler();
}
}
return null;
}
public CommandContextFactory getCommandContextFactory() {
return commandContextFactory;
}
public void setCommandContextFactory(CommandContextFactory commandContextFactory) {
this.commandContextFactory = commandContextFactory;
}
public ProcessEngineConfigurationImpl getProcessEngineConfiguration() {
return processEngineConfiguration;
}
public void setProcessEngineContext(ProcessEngineConfigurationImpl processEngineContext) {
this.processEngineConfiguration = processEngineContext;
}
}
5.命令执行器接口实现
package org.activiti.engine.impl.cfg;
import org.activiti.engine.impl.interceptor.Command;
import org.activiti.engine.impl.interceptor.CommandConfig;
import org.activiti.engine.impl.interceptor.CommandExecutor;
import org.activiti.engine.impl.interceptor.CommandInterceptor;
/**
* Command executor that passes commands to the first interceptor in the chain. If no {@link CommandConfig} is passed, the default configuration will be used.
*
* @author Marcus Klimstra (CGI)
* @author Joram Barrez
*/
public class CommandExecutorImpl implements CommandExecutor {
protected CommandConfig defaultConfig;
protected CommandInterceptor first;
public CommandExecutorImpl(CommandConfig defaultConfig, CommandInterceptor first) {
this.defaultConfig = defaultConfig;
this.first = first;
}
public CommandInterceptor getFirst() {
return first;
}
public void setFirst(CommandInterceptor commandInterceptor) {
this.first = commandInterceptor;
}
@Override
public CommandConfig getDefaultConfig() {
return defaultConfig;
}
@Override
public <T> T execute(Command<T> command) {
return execute(defaultConfig, command);
}
@Override
public <T> T execute(CommandConfig config, Command<T> command) {
return first.execute(config, command);
}
}
6.初始化拦截器
public void initCommandExecutors() {
initDefaultCommandConfig();
initSchemaCommandConfig();
initCommandInvoker();
initCommandInterceptors();
initCommandExecutor();
}
public void initCommandInterceptors() {
if (commandInterceptors == null) {
commandInterceptors = new ArrayList<CommandInterceptor>();
if (customPreCommandInterceptors != null) {
commandInterceptors.addAll(customPreCommandInterceptors);
}
commandInterceptors.addAll(getDefaultCommandInterceptors());
if (customPostCommandInterceptors != null) {
commandInterceptors.addAll(customPostCommandInterceptors);
}
commandInterceptors.add(commandInvoker);
}
}
public void initCommandExecutor() {
if (commandExecutor == null) {
CommandInterceptor first = initInterceptorChain(commandInterceptors);
commandExecutor = new CommandExecutorImpl(getDefaultCommandConfig(), first);
}
}
public CommandInterceptor initInterceptorChain(List<CommandInterceptor> chain) {
if (chain == null || chain.isEmpty()) {
throw new ActivitiException("invalid command interceptor chain configuration: " + chain);
}
for (int i = 0; i < chain.size() - 1; i++) {
chain.get(i).setNext(chain.get(i + 1));
}
return chain.get(0);
}
7. 拦截器执行
通过执行commandExecutor的execute方法执行拦截器，在activiti中用于执行各种服务时都要执行拦截器
// services
// /////////////////////////////////////////////////////////////////
public void initServices() {
initService(repositoryService);
initService(runtimeService);
initService(historyService);
initService(identityService);
initService(taskService);
initService(formService);
initService(managementService);
initService(dynamicBpmnService);
}
//commandExecutor作为service的一个属性传入
public void initService(Object service) {
if (service instanceof ServiceImpl) {
((ServiceImpl) service).setCommandExecutor(commandExecutor);
}
}
serviceImpl的实现
package org.activiti.engine.impl;
import org.activiti.engine.impl.cfg.ProcessEngineConfigurationImpl;
import org.activiti.engine.impl.interceptor.CommandExecutor;
/**
* @author Tom Baeyens
* @author Joram Barrez
*/
public class ServiceImpl {
protected ProcessEngineConfigurationImpl processEngineConfiguration;
public ServiceImpl() {
}
public ServiceImpl(ProcessEngineConfigurationImpl processEngineConfiguration) {
this.processEngineConfiguration = processEngineConfiguration;
}
protected CommandExecutor commandExecutor;
public CommandExecutor getCommandExecutor() {
return commandExecutor;
}
public void setCommandExecutor(CommandExecutor commandExecutor) {
this.commandExecutor = commandExecutor;
}
}
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