Android相关小技术代码.doc

检查网络是否连接上Java代码 1. /* 2. *检测网络是否连接（注：需要在配置文件即AndroidManifest.xml加入权限） 3. * 4. *paramcontext 5. *returntrue:网络连接成功 6. *returnfalse:网络连接失败 7. */ 8. publicstaticbooleanisConnect(Contextcontext) 9. /获取手机所有连接管理对象（包括对wi-fi,net等连接的管理） 10. ConnectivityManagerconnectivity=(ConnectivityManager)context 11. .getSystemService(Context.CONNECTIVITY_SERVICE); 12. if(connectivity!=null) 13. /获取网络连接管理的对象 14. NetworkInfoinfo=connectivity.getActiveNetworkInfo(); 15. if(info!=null) 16. /判断当前网络是否已经连接 17. if(info.getState()=NetworkInfo.State.CONNECTED) 18. returntrue; 19. 20. 21. 22. returnfalse; 23. =函数用于判断网络是否可用Java代码 1. /* 2. *returnbooleanreturntrueiftheapplicationcanaccesstheinternet 3. */ 4. privatebooleanhaveInternet() 5. NetworkInfoinfo=(ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE).getActiveNetworkInfo(); 6. if(info=null|!info.isConnected() 7. returnfalse; 8. 9. if(info.isRoaming() 10. /hereistheroamingoptionyoucanchangeitifyouwanttodisableinternetwhileroaming,justreturnfalse 11. returntrue; 12. 13. returntrue; 14. 需要注意的是有关调用需要加入 这个权限，android开发网提醒大家在真机上Market和Browser程序都使用了这个方法，来判断是否继续，同时在一些网络超时的时候也可以检 查下网络连接是否存在，以免浪费手机上的电力资源。浅析android下如何通过jni监控wifi网络连接、dhcpcd执行和power电源控制=libs/android_runtime/android_net_wifi_Wifi.cpp部分jni接口static JNINativeMethod gWifiMethods = loadDriver, ()Z, (void *)android_net_wifi_loadDriver , setPowerModeCommand, (I)Z, (void*) android_net_wifi_setPowerModeCommand ,/电源管理 connectToSupplicant, ()Z, (void *)android_net_wifi_connectToSupplicant , waitForEvent, ()Ljava/lang/String;, (void*) android_net_wifi_waitForEvent , disconnectCommand, ()Z, (void *)android_net_wifi_disconnectCommand , .;int register_android_net_wifi_WifiManager(JNIEnv* env) . return AndroidRuntime:registerNativeMethods(env, WIFI_PKG_NAME, gWifiMethods, NELEM(gWifiMethods);/登记jnilibs/android_runtime/AndroidRuntime.cppstatic const RegJNIRec gRegJNI = . REG_JNI(register_android_net_wifi_WifiManager), .;int AndroidRuntime:startReg(JNIEnv* env) . register_jni_procs(gRegJNI, NELEM(gRegJNI), env); .AndroidRuntime:start=startReg(env)即调用方法int AndroidRuntime:startReg(JNIEnv* env)=wifi_load_driverwifi_start_supplicant=ensure_config_file_exists/检查/data/misc/wifi/wpa_supplicant.conf文件是否存在,如果不存在,那么从/system/etc/wifi/wpa_supplicant.conf动态拷贝一份android_net_wifi_connectToSupplicant=wifi_connect_to_supplicant= ctrl_conn = wpa_ctrl_open(ifname); monitor_conn = wpa_ctrl_open(ifname); wpa_ctrl_attach(monitor_conn);android_net_wifi_waitForEvent=wifi_wait_for_event=wpa_ctrl_recv(monitor_conn, buf, &nread);=recv(ctrl-s, reply, *reply_len, 0);/阻塞等待wpa_supplicant的netlink数据过来=如果接收的buf数据区,buf0为,那么说明有level级别信息,所以将数据剔除,然后wifi_wait_for_event函数返回luther.gliethttp.java/android/android/net/wifi/WifiMonitor.javapublic class WifiMonitor . public void startMonitoring() new MonitorThread().start();/启动java线程 class MonitorThread extends Thread public MonitorThread() super(WifiMonitor); public void run() for (;) ensureSupplicantConnection();/=WifiNative.connectToSupplicant调用jni函数android_net_wifi_connectToSupplicant String eventStr = WifiNative.waitForEvent();/=调用jni函数android_net_wifi_waitForEvent /private static final int CONNECTED = 1; /private static final int DISCONNECTED = 2; /private static final String eventPrefix = CTRL-EVENT-; /private static final int eventPrefixLen = eventPrefix.length(); /private static final String connectedEvent = CONNECTED; /private static final String disconnectedEvent = DISCONNECTED; String eventName = eventStr.substring(eventPrefixLen);/去掉CTRL-EVENT-字符串 int nameEnd = eventName.indexOf( );/找到随后的空格位置,这在wpa_supplicant发送时/#define WPA_EVENT_CONNECTED CTRL-EVENT-CONNECTED 中,已经内置空格了. if (nameEnd != -1) eventName = eventName.substring(0, nameEnd); int event; if (eventName.equals(connectedEvent)/检测netlink过来的字符串action类型 event = CONNECTED; else if (eventName.equals(disconnectedEvent) event = DISCONNECTED; . int ind = eventStr.indexOf( - );/CTRL-EVENT-CONNECTED - Connection to . if (ind != -1) eventData = eventStr.substring(ind + 3);/剔除前导控制字符,将 - 后面的描述字符串作为真实数据,继续处理 . if (event = STATE_CHANGE) handleSupplicantStateChange(eventData); else if (event = DRIVER_STATE) handleDriverEvent(eventData); else handleEvent(event, eventData);/对于CONNECTED和DISCONNECTED等netlink事件将执行此操作来处理luther.gliethttp / If supplicant is gone, exit the thread if (event = TERMINATING) break; . void handleEvent(int event, String remainder) switch (event) case DISCONNECTED: handleNetworkStateChange(NetworkInfo.DetailedState.DISCONNECTED, remainder); break; 本篇文章来源于：开发学院 原文链接：/2009/1231/19239.phpcase CONNECTED: handleNetworkStateChange(NetworkInfo.DetailedState.CONNECTED, remainder);/控制界面显示 break; .public class WifiStateTracker extends NetworkStateTracker . public void startEventLoop() mWifiMonitor.startMonitoring();/启动上面的MonitorThread线程 .java/services/com/android/server/WifiService.javapublic class WifiService extends IWifiManager.Stub . private boolean setWifiEnabledBlocking(boolean enable) final int eventualWifiState = enable ? WIFI_STATE_ENABLED : WIFI_STATE_DISABLED; . if (enable) if (WifiNative.loadDriver() Log.e(TAG, Failed to load Wi-Fi driver.); updateWifiState(WIFI_STATE_UNKNOWN); return false; if (WifiNative.startSupplicant() WifiNative.unloadDriver(); Log.e(TAG, Failed to start supplicant daemon.); updateWifiState(WIFI_STATE_UNKNOWN); return false; mWifiStateTracker.startEventLoop();/启动MonitorThread线程,等待wpa_supplicant将netlink数据转发过来,然后根据netlink动作类型,进一步影响界面显示luther.gliethttp. .java/android/android/net/wifi/WifiStateTracker.java电源管理private void handleConnectedState() . mDhcpTarget.obtainMessage(EVENT_DHCP_START).sendToTarget();/传递到下面的handleMessage方法 .public void onChange(boolean selfChange) . handleConnectedState(); .public class WifiStateTracker extends NetworkStateTracker . public void handleMessage(Message msg) switch (msg.what) case EVENT_SUPPLICANT_CONNECTION: case EVENT_NETWORK_STATE_CHANGED: handleConnectedState();/调用 . private class DhcpHandler extends Handler private Handler mTarget; public DhcpHandler(Looper looper, Handler target) super(looper); mTarget = target; public void handleMessage(Message msg) int event; /private static final int DRIVER_POWER_MODE_AUTO = 0; /private static final int DRIVER_POWER_MODE_ACTIVE = 1; switch (msg.what) case EVENT_DHCP_START: synchronized (this) WifiNative.setPowerModeCommand(DRIVER_POWER_MODE_ACTIVE);/设置电源模式,调用android_net_wifi_setPowerModeCommand Log.d(TAG, DhcpHandler: DHCP request started);/libs/android_runtime/android_net_NetUtils.cpp/static JNINativeMethod gNetworkUtilMethods = / runDhcp, (Ljava/lang/String;Landroid/net/DhcpInfo;)Z, (void *)android_net_utils_runDhcp ,/ ./; 本篇文章来源于：开发学院 原文链接：/2009/1231/19239_2.phpif (NetworkUtils.runDhcp(mInterfaceName, mDhcpInfo) /执行dhcp申请ip地址操作 event = EVENT_INTERFACE_CONFIGURATION_SUCCEEDED; if (LOCAL_LOGD) Log.v(TAG, DhcpHandler: DHCP request succeeded); else event = EVENT_INTERFACE_CONFIGURATION_FAILED; Log.i(TAG, DhcpHandler: DHCP request failed: + NetworkUtils.getDhcpError();/如果dhcpcd分配ip失败,那么Message.obtain(mTarget, event).sendToTarget();将执行/WifiNative.disconnectCommand();即：static JNINativeMethod gWifiMethods = /android_net_wifi_disconnectCommand发送DISCONNECT字符串luther.gliethttp/然后在wpa_supplicant服务端执行wpa_supplicant_ctrl_iface_process/wpa_supplicant_disassociate synchronized (this) WifiNative.setPowerModeCommand(DRIVER_POWER_MODE_AUTO); Message.obtain(mTarget, event).sendToTarget(); break; . /* * Send the tracker a notification that a connection to the supplicant * daemon has been established. */在上面的public class WifiMonitor=ensureSupplicantConnection/=/while (!supplicantConnected) / boolean connected;/synchronized (mWifiStateTracker) /connected = WifiNative.connectToSupplicant();/如果没有连接成功,那么while循环尝试,直到尝试成功,或者定义了oneShot,仅一次尝试/=mWifiStateTracker.notifySupplicantConnection();/如果WifiNative.connectToSupplicant()成功,那么将执行/mWifiStateTracker.notifySupplicantConnection();的调用. void notifySupplicantConnection() /向对象发送message Message.obtain(this, EVENT_SUPPLICANT_CONNECTION).sendToTarget(); void notifyStateChange(SupplicantState newState) Message.obtain(this, EVENT_SUPPLICANT_STATE_CHANGED, newState).sendToTarget(); .static jboolean android_net_wifi_setPowerModeCommand(JNIEnv* env, jobject clazz, jint mode) char cmdstr256; sprintf(cmdstr, DRIVER POWERMODE %d, mode); return doBooleanCommand(cmdstr, OK);android_net_wifi_setPowerModeCommand=doBooleanCommand=doCommand=wifi_command=wifi_send_command=wpa_ctrl_request=send给wpa_supplicant然后wpa_supplicant将做如下接收操作：system/extra/wpa_supplicant/main.c=wpa_supplicant_add_iface=wpa_supplicant_init_iface2=wpa_supplicant_ctrl_iface_init=注册ctrl_conn控制端口和monitor_conn监听端口的处理函数 eloop_register_read_sock(priv-sock, wpa_supplicant_ctrl_iface_receive, wpa_s, priv);/ctrl_conn端口的handler处理函数 wpa_msg_register_cb(wpa_supplicant_ctrl_iface_msg_cb);/monitor_conn端口的回调处理函数,处理netlink数据到所有monitor_conn监听端口=wpa_supplicant_ctrl_iface_receive/对于unix通信方式=wpa_supplicant_ctrl_iface_process=如果wpa_cli发送的是wpa_cli driver xxx形式的命令,那么调用这个函数if (os_strncmp(buf, DRIVER , 7) = 0) /掠过前7个,直接将命令传过去reply_len = wpa_supplicant_driver_cmd(wpa_s, buf + 7, reply, reply_size);=wpa_supplicant_driver_cmd=wpa_drv_driver_cmd=自定义DRIVER扩展处理函数,所以对于java传递过来的power电源管理命令,wpa_drv_driver_cmd将收到POWERMODE 0或者POWERMODE 1字符串luther.gliethttp=jni=runDhcp=android_net_utils_runDhcplibs/netutils/dhcp_utils.c=dhcp_do_request= static const char DAEMON_NAME = dhcpcd; static const char DAEMON_PROP_NAME = init.svc.dhcpcd; static const char DHCP_PROP_NAME_PREFIX = dhcp; const char *ctrl_prop = ctl.start; const char *desired_status = running; snprintf(result_prop_name, sizeof(result_prop_name), %s.%s.result, DHCP_PROP_NAME_PREFIX, interface); property_set(result_prop_name, );/设置dhcp.eth0.result=;等到成功完成dhcp之后, property_set(ctrl_prop, DAEMON_NAME);/向名字为dhcpcd的service,发送ctrl.start启动命令字,该service在init.rc中/init.rc中dhcpcd服务进程命令字/service dhcpcd /system/bin/dhcpcd eth0/ disabled/ oneshot wait_for_property(DAEMON_PROP_NAME, desired_status, 10);/init.c=init进程/=handle_property_set_fd因为是ctrl.start命令字,所以调用handle_control_message处理控制信息/=handle_control_message/=msg_start/=/ struct service *svc = service_find_by_name(name);/ service_start(svc);/启动svc,即执行：/system/bin/dhcpcd eth0/=service_start/=pid = fork();/ if(pid = 0)execve(svc-args0, (char*) svc-args, (char*) ENV);子进程执行execve运行/system/bin/dhcpcd,参数为eth0/=否则父进程,即init进程将/=notify_service_state(svc-name, running);设置该svc的状态prop/ snprintf(pname, sizeof(pname), init.svc.%s, name);/ property_set(pname, state);/所以这样上面wait_for_property(DAEMON_PROP_NAME, desired_status, 10);也才能够正常passluther.gliethttp. wait_for_property(result_prop_name, NULL, 15);/等待dhcp.eth0.result=非空=system/extra/dhcpcd-4.0.0-beta9/dhcpcd.cdhcpcd=main# define SYSCONFDIR /system/etc/dhcpcd#define PACKAGE dhcpcd# define CONFIG SYSCONFDIR / PACKAGE .conf# define LIBEXECDIR /system/etc/dhcpcd# define SCRIPT LIBEXECDIR / PACKAGE -run-hooks=strlcpy(options-script, SCRIPT, sizeof(options-script);/默认的options-script=/system/etc/dhcpcd/dhcpcd-run-hooks=f = fopen(cf ? cf : CONFIG, r);/如果没有指定.conf文件,那么使用默认.conf文件=parse_config_line/解析/system/etc/dhcpcd/dhcpcd.conf默认配置文件=parse_option=如果在/system/etc/dhcpcd/dhcpcd.conf有script这个节=那么执行strlcpy(options-script, oarg, sizeof(options-script);直接拷贝/*script, required_argument, NULL, c,option, required_argument, NULL, o,/system/etc/dhcpcd/dhcpcd.conf中的部分内容如下：.option domain_name_servers, domain_name, domain_search, host_name.*/=dhcp_run=handle_dhcp_packet=handle_dhcp=bind_dhcp reason = TIMEOUT;reason = BOUND;reason = REBIND;reason = RENEW;system/extra/dhcpcd-4.0.0-beta9/configure.c= configure(iface, reason, state-new, state-old, &state-lease, options, 1);/如果dhcp超时或者dhcp成功,都会调用exec_script来执行脚本,/执行setprop dhcp.$interface.result failed或者/执行setprop dhcp.$interface.result ok=exec_script(options, iface-name, reason, NULL, old);=然后configure_env通过环境变量将reason传递到脚本中int exec_script(const struct options *options, const char *iface, const char *reason, const struct dhcp_message *dhcpn, const struct dhcp_message *dhcpo)=pid = fork();=if(pid = 0)execve(options-script, argv, env);/子进程执行脚本,默认/system/etc/dhcpcd/dhcpcd-run-hooks/dhcpcd-run-hooks脚本会根据level值,决定是否执行system/etc/dhcpcd/dhcpcd-hook/*目录下的相应文件/我们的系统在该system/etc/dhcpcd/dhcpcd-hook/*目录下有如下3个文件/95-configured/20-dns.conf/01-test=父进程返回while (waitpid(pid, &status, 0) = -1)等待子进程脚本执行完成本篇文章来源于：开发学院 原文链接：/2009/1231/19239_3.phpsystem/extra/dhcpcd-4.0.0-beta9/dhcpcd-hooks/20-dns.confsystem/extra/dhcpcd-4.0.0-beta9/dhcpcd-hooks/95-configured . setprop dhcp.$interface.ipaddress $new_ip_address setprop dhcp.$interface.result ok/设置属性为ok setprop dhcp.$interface.result failed .=inet_init、tcp_protsock-ops-sendmsg(iocb, sock, msg, size);=inetsw_array=inet_stream_ops=tcp_sendmsg=wpa_cli.c=main=wpa_cli_interactive=wpa_cli_recv_pending(monitor_conn, 0, 0);/阻塞等待wpa_supplicant发送数据过来=如果action_monitor为true,那么将执行一些简单加工操作,否则将直接将wpa_supplicant发过来的数据打印到console上luther.gliethttp. 本篇文章来源于：开发学院 原文链接：/2009/1231/19239_4.phpAndroid操作系统并没有提供任务管理器程序，无从得知后台有哪些程序正在运行。本范例是通过ActivityManager.getRunningTasks方法来取得正在运行中的工作程序，并使用ListView将之罗列出来。 这里说的“正在运行”是指单击“按钮”时所获取到的信息，如果放在ListView里的工作已经结束，或者被操作系统回收（Garbage Collection，GC），此时是不会更新运行列表的，而由于没有其他运行中工作的访问权限，因此也不能通过本程序关闭。 在以下范例的Layout里，设计一个TextView、一个ListView以及一个按钮，通过按钮单击的事件，同时向系统ActivityManager取出正在运行的Activity Tasks。 范例程序 src/irdc.ex05_21/EX05_21.java 在访问系统Activity的运行工作时，必须指定要取得的工作数量，因为资源有限，所以在类成员中设置了最多取出30笔的Activity运行工作。 单击按钮之后，便会使得私有类成员mActivityManager重新向系统