http断点续传简单实现（java)

/* t~7OtPF  
**SiteFileFetch.java 0 N"N$f  
*/ 'hE'h
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package NetFox; qA;Gl"HF  
import java.io.*; uu9IUqEq2  
import java.net.*; (\D E1q  
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public class SiteFileFetch extends Thread { "~=-Q#xO  
Nm !~h|3  
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SiteInfoBean siteInfoBean = null; //文件信息Bean eF]8Ar1  
long[] nStartPos; //开始位置 y XKddD  
long[] nEndPos; //结束位置 s
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FileSplitterFetch[] fileSplitterFetch; //子线程对象 $*VZa3B\  
long nFileLength; //文件长度 06O_!"GD}  
boolean bFirst = true; //是否第一次取文件 
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boolean bStop = false; //停止标志 *|<T@BXn  
File tmpFile; //文件下载的临时信息 3dSb!q0&N  
DataOutputStream output; //输出到文件的输出流 (i L*1f   
8v z h5,U  
//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） D Qz+t  
public SiteFileFetch(SiteInfoBean bean) throws IOException k3H0$1  
{ DF_wMv:>^  
siteInfoBean = bean; =&6sU{j*  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); .%y'q!?  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); ;>>n#8
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if(tmpFile.exists ()) Th$Z9+()  
{ ?"*JV1 9  
bFirst = false; 9/!1J  
read_nPos(); <#J5.I 1  
} OLPY<ax  
else $[}EV(#y  
{ F~i ~%f,  
nStartPos = new long[bean.getNSplitter()]; 4(sHUWT  
nEndPos = new long[bean.getNSplitter()]; d!w3LwZ  
} J$sBfOD  
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} V y$*v  
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public void run() J^`5L7CO  
{ -uWV( ,|  
//获得文件长度 q\}+]|nGs  
//分割文件 ,cL;,YN  
//实例FileSplitterFetch 5@%.wb4  
//启动FileSplitterFetch线程 4uzMO<  
//等待子线程返回 {aNpk,n  
try{ R|}N"J_  
if(bFirst) 1cv~_jFh  
{ gs;^SRE I  
nFileLength = getFileSize(); 0Dna+V/jI  
if(nFileLength == -1) g9q}D-  
{ O>pv/Ns  
System.err.println("File Length is not known!"); ^ZO! (  
} &oMWs]0  
else if(nFileLength == -2) a/\{NHs6"5  
{ }^iqhUvT F  
System.err.println("File is not access!"); *2u~5Kc<  
} BGBHA"5fz  
else }dop]{RG  
{ EwX&Cj".  
for(int i=0;i<nStartPos.length;i++) |dqHpogh  
{ vue^bn  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); * eC[74Kng  
} );':aXj  
for(int i=0;i<nEndPos.length-1;i++) +^lB"OcOX@  
{ m)} 01N4  
nEndPos = nStartPos[i+1]; tnaFbmp  
} cL
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nEndPos[nEndPos.length-1] = nFileLength; u*v<dsGQ  
} =V]0G,,\  
} BaW4 s4u  
\?>M?6D  
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//启动子线程 '
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fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; chKK9SC+|  
for(int i=0;i<nStartPos.length;i++) /
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{ !}z'"l4i  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Q8%_q"C  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), ?T2>juf]5~  
nStartPos,nEndPos,i); nV7Vc;  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); o^vX\a?`u  
fileSplitterFetch.start(); l@Vv%w9H  
} uyxYCc  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), 7Vsp<s9bj  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); HK8sn1j  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", gr SF}y!3  
nEndPos = " + nFileLength); m9oOH5@K~  
// fileSplitterFetch[nPos.length-1].start(); H:]cBk^[,  
{?eUAB<  
<kdlXS>J.  
//等待子线程结束 3}<U'%sd  
//int count = 0; zk FX[-'O  
//是否结束while循环 N=BG0t$  
boolean breakWhile = false; (_zlCHB  
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>< $LV&  
while(!bStop) WA8<:#{e  
{ @wgd 3BU  
write_nPos(); #dj?^n g
 
Utility.sleep(500); uy'seJ  
breakWhile = true; )rK2%\Z  
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for(int i=0;i<nStartPos.length;i++) x{SlJ%V  
{ x_nwD"   
if(!fileSplitterFetch.bDownOver) WJOoDS!i  
{ (MI>7| ';  
breakWhile = false; \4q|Qno8  
break; qK a}O*  
} GYfOwV!zB  
} [|OII!"  
if(breakWhile) P[WkW#  
break; HCs^?s8Pp  
+QU>D:l  
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//count++; (c(F1=K  
//if(count>4)
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// siteStop(); ;"Kgg:K>W  
} 5,1<A@H  
0cq@lT6  
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System.err.println("文件下载结束！"); 93HVx#  
} P>C'?'Q7  
catch(Exception e){e.printStackTrace ();} i=aR~
  
} L'e^D|  
&/? Ct!_  
l~rj7f;  
//获得文件长度 }_]AQN$'G  
public long getFileSize() e{5?+6KH  
{ c4Zpt%:}h  
int nFileLength = -1; TwPQ8}pj?  
try{ jr4xh{Z`  
URL url = new URL(siteInfoBean.getSSiteURL()); 
:3n@].  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); y("WnVI  
httpConnection.setRequestProperty("User-Agent","NetFox"); ;>v.(0FE6  
/h0
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int responseCode=httpConnection.getResponseCode(); ^-_*@e*JE  
if(responseCode>=400) 1.cP3kl  
{ )x|;%.8FX7  
processErrorCode(responseCode); -`~qmRpqY  
return -2; //-2 represent access is error `N *:,8j  
} A)&FcMO*z  
s$R /!,c  
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String sHeader; ={O ~  
:Z//  
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for(int i=1;;i++) _J l(:r\%  
{ {Yj5Mj|#  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); OoSk^U)  
//Utility.log(in.readLine()); ,-#MEr  
sHeader=httpConnection.getHeaderFieldKey(i); mVZh_R=a  
if(sHeader!=null) !CGX\cvW  
{ "tz6O0D  
if(sHeader.equals("Content-Length")) W%!(kN&d  
{ 8wsU`40=Q  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); 0>sa
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break; 9GD0jJEu  
} {cm?Q\DT  
} _RbfyyaN  
else fCr2'+O"b  
break; d.wGO]"  
} '47 b"uV  
} o&?c,FwN  
catch(IOException e){e.printStackTrace ();} UX)GA[WI  
catch(Exception e){e.printStackTrace ();} .11l(M  
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Utility.log(nFileLength); ?F"o+]i+^  
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return nFileLength; F^yW3|Sb  
} &h334N|4{  
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//保存下载信息（文件指针位置） aA`eKy) \  
private void write_nPos() UBaXS_c\  
{ b#6S8C+@  
try{ * 65/gG8>  
output = new DataOutputStream(new FileOutputStream(tmpFile)); f7=MgFi  
output.writeInt(nStartPos.length); 24jf`1XFW  
for(int i=0;i<nStartPos.length;i++) Mn0.!J "  
{ \OwF!~&  
// output.writeLong(nPos); VgHO&vU  
output.writeLong(fileSplitterFetch.nStartPos); op6]"ZV-C  
output.writeLong(fileSplitterFetch.nEndPos); g*V.u]U!i  
} fkxkf^g)  
output.close(); 1q}L
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} V:n0BlZ,B  
catch(IOException e){e.printStackTrace ();} a"vzC$Hxd  
catch(Exception e){e.printStackTrace ();} +4?Lwp'q  
} {iD/0q  
<]
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//读取保存的下载信息（文件指针位置） ZJ/528Ju  
private void read_nPos() J>Ar(p  
{ LDt6<D8,Q  
try{ A,~3oQV  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); B7%,D}  
int nCount = input.readInt(); FuHBzBoM=  
nStartPos = new long[nCount]; %ih\|jRt  
nEndPos = new long[nCount]; i KSRr#/  
for(int i=0;i<nStartPos.length;i++) ea
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{ d0aXA+S%  
nStartPos = input.readLong(); Qte5E}V`  
nEndPos = input.readLong(); =g#PP@X]D!  
} hG1$YE  
input.close(); bY~K)j v3&  
} ?qjdmB|w  
catch(IOException e){e.printStackTrace ();} OgF[=  
catch(Exception e){e.printStackTrace ();} CD`a-]6qA  
} g NI1W@)  
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private void processErrorCode(int nErrorCode) <XeDJ8 '  
{ N^;lp<{6?  
System.err.println("Error Code : " + nErrorCode); HWjJ.;k}a  
} ^z *0  
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//停止文件下载 K"!rj.Da  
public void siteStop() R$:-~<O  
{ @@Q4{o  
bStop = true; zIc6L3w$  
for(int i=0;i<nStartPos.length;i++) DsdM:u*s  
fileSplitterFetch.splitterStop(); fQoAdw  
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} !:+U-mb*  
} tV++QC7@L  
//负责部分文件的抓取 k\OZ'dS  
**FileSplitterFetch.java j7P49{  
*/ ~^F]t$rz  
package NetFox; yX&# rI  
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a ,mgM&yD  
import java.io.*; }9@rhW  
import java.net.*; ^%\a,~  
,+i^]yF3j  
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public class FileSplitterFetch extends Thread { ?
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String sURL; //File URL D^r g-E[L  
long nStartPos; //File Snippet Start Position +Nn >*sz  
long nEndPos; //File Snippet End Position >@N.jw>#T  
int nThreadID; //Thread's ID 1]}\h]*  
boolean bDownOver = false; //Downing is over !&U75FpN}:  
boolean bStop = false; //Stop identical _c]}m3/  
FileAccessI fileAccessI = null; //File Access interface ]T
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException ]@U?hD  
{ SqAz((  
this.sURL = sURL; nDkG}JkB!  
this.nStartPos = nStart; (Q{JI~P  
this.nEndPos = nEnd; e{8C0=  
nThreadID = id;  V FM[-  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 ?c.\\2>|F  
} o
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public void run() LNL}R[1(  
{  *RY}e  
while(nStartPos < nEndPos && !bStop) g!0 j1  
{ 
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try{ wGO-Z']i  
URL url = new URL(sURL); H;=yR]E  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Yyk~!G/@  
httpConnection.setRequestProperty("User-Agent","NetFox"); sD3Ts;k  
String sProperty = "bytes="+nStartPos+"-"; }%KQrlbHJl  
httpConnection.setRequestProperty("RANGE",sProperty); "|6(.S+o  
Utility.log(sProperty); >D=X Tgqqq  
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InputStream input = httpConnection.getInputStream(); S(=@2A+;  
//logResponseHead(httpConnection); <@7j37,R7V  
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byte[] b = new byte[1024]; |mhKD#:  
int nRead; CQ!D{o=  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ^(Gl$GC$Mu  
{ ejg!1*H@n  
nStartPos += fileAccessI.write(b,0,nRead); xEG:KSH  
//if(nThreadID == 1) v0'z''KM!  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); I>MLI=[Kg  
} +^:uPW^U  
7gtaI3   
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Utility.log("Thread " + nThreadID + " is over!"); qRT5|\l  
bDownOver = true; Fmn_fW6  
//nPos = fileAccessI.write (b,0,nRead); tdU'cc?M  
} ,,FhE  
catch(Exception e){e.printStackTrace ();}
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} 8?~>FLWTXZ  
} SP0ueAa}  
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//打印回应的头信息 .t^1
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public void logResponseHead(HttpURLConnection con) `~axOp9N  
{ S?DMeZ{:  
for(int i=1;;i++) ;180ct4  
{ J?p|Vy|9  
String header=con.getHeaderFieldKey(i); s]vsD77&  
if(header!=null) *<9M|H~  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); $hM9{  
Utility.log(header+" : "+con.getHeaderField(header)); 0Dd8c\J  
else BT:b&"AR[  
break; Vl7V?`_4  
} ^b&hy&ag  
} g6q[ I8  
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public void splitterStop() kaZcYuT.9  
{ Dmtsu2o  
bStop = true; F0xm%?  
} &WbHM)_n  
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} <SRSJJR|(  
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/* ipiS=  
**FileAccess.java i .?l\  
*//文件访问(定位，写) CwF=@:*d  
package NetFox; o>M&C X+j$  
import java.io.*; `?N|{kb  
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public class FileAccessI implements Serializable{ CfLPs)\ACm  
q_6<}2m,U  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 0@!-+}i  
RandomAccessFile oSavedFile; =rNI&K_<  
long nPos; S?H qrf7<  
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public FileAccessI() throws IOException ^O5PcV3Eg  
{ EU7mP MxJ  
this("",0); r-}C !aF]  
} }8'bXG+  
i/DUB<>p6  
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public FileAccessI(String sName,long nPos) throws IOException CIt@xi#I  
{ Cp-p7g0wlg  
oSavedFile = new RandomAccessFile(sName,"rw"); p-8x>dmP(  
this.nPos = nPos; {NIE:MXX  
oSavedFile.seek(nPos); &W y9%  
} 2)`4(38  
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public synchronized int write(byte[] b,int nStart,int nLen) [{-;cpM\  
{ K30{Fcb< h  
int n = -1; M[dJQ(  
try{ _K>YB>W}7  
oSavedFile.write(b,nStart,nLen); cr{f*U6`  
n = nLen; SR'u*u!  
} Y&b JKX  
catch(IOException e) a/ Z\h{*  
{ {Ve_u  
e.printStackTrace (); H|!|fo-Tx  
} pL'+sW  
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"\Nn,3qp  
return n; , rc %#eF  
} "M:0lUy  
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} &p^8zEs  
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/* jUX0sRDk  
**SiteInfoBean.java czp}-{4X  
*/ |rk4,
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package NetFox; -6>T0-  
7%^/Jm  
^5*9BwH`  
public class SiteInfoBean { ||kUi=5  
|Xk>a7X  
odpjEeQC  
private String sSiteURL; //Site's URL
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private String sFilePath; //Saved File's Path >*goDtTjp  
private String sFileName; //Saved File's Name %:]ive]e  
private int nSplitter; //Count of Splited Downloading File B=+Py%  
0h~7"qUF@  
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public SiteInfoBean() b$1W>  
{//nSplitter的缺省值为5 .qk_m-o  
//default value of nSplitter is 5 aRF}FE,u  
this("","","",5); R<x~KJ11c  
} \B~}s}  
u IGeSd5B  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) <C,lHt  
{ &C=[D_h  
sSiteURL= sURL; aqzIMOAf  
sFilePath = sPath; #)N}F/Od^  
sFileName = sName; h"DxgG  
this.nSplitter = nSpiltter; "xKykSk  
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} (7_}UT@w-  
^9*kZV<K  
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public String getSSiteURL() Zf~Z&"C)  
{ @is!VzE  
return sSiteURL; .8EaFEd  
} vhOX1'  
{gwJ>]z"e  
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public void setSSiteURL(String value) oF0BBs$  
{ s/0S]P]}f  
sSiteURL = value; .>Fy ]Cqoh  
} ^>ICycJ  
&3_.k  
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public String getSFilePath() 
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{ [Y_CRxa\u  
return sFilePath; i~0x/wSl_  
} T>2_r6;  
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public void setSFilePath(String value) 'Wz`P#/  
{ 6=o'.03\f  
sFilePath = value; Ods/1 KW  
} lrL:v~g  
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public String getSFileName() %!r@l7<  
{ U8
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return sFileName; A5[iFT
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} M\rZr3  
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public void setSFileName(String value) f5ttQ&@FF  
{ C_ 4(-OWq  
sFileName = value; JULns#tx}  
} {\62c;.  
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public int getNSplitter() 3JJE
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{ @zGz8IF  
return nSplitter; =)mA.j}E2  
} I->BDNk  
^ 9`O ^  
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public void setNSplitter(int nCount) D@ 4sq^|2  
{ ?)V?6"fFP  
nSplitter = nCount; ^Ez`WP  
} |Jpi|'  
} aF]cEe  
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/* V krjs0  
**Utility.java gHmy?+)  
*/ (29BS(|!  
package NetFox; 6[~_;0  
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public class Utility { eRm 9LOp  
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public Utility() DT#F?@LG(  
{ e` {F7rd:  
}2+*E}g  
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} '?)<e^  
*aaK_=w  
//线程睡眠 F*TkQ\y  
public static void sleep(int nSecond) m[8?d~  
{ ZXH{9hxd  
try{ /n-!dXi  
Thread.sleep(nSecond); o7sIpE9  
} - xKa-3  
catch(Exception e) gPqdl6#c  
{ U]}f]GK  
e.printStackTrace (); >#[,OU}N  
} o/4U`U)Q0v  
} (t_%8Eu  
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//日志 >&`;@ZOH  
public static void log(String sMsg) ;5!M+nk  
{ U#>K(  
System.err.println(sMsg); 'Hv=\p4$1  
} teX)!N [  
'
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public static void log(int sMsg) 2qpUUo f  
{ M T]2n{e  
System.err.println(sMsg); 4D=^24f`0  
} Aw"Y_S8.  
} /ht-]Js$G  
*Eg[@5;QA  
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/* B:rzM:BQ  
**TestMethod.java Scd_tw.]|  
*/ F~;UD<<"H  
package NetFox; |{ TVW  
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public class TestMethod { SbK6o:[  
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public TestMethod() \#7@"~<  
{ ///xx/weblogic60b2_win.exe G7SmlFn?  
try{ ;GV~MH-F  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); [5i}C K_=  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 2}0S%R(  
SiteFileFetch fileFetch = new SiteFileFetch(bean); /vNHb_-  
fileFetch.start(); ' o(7@   
} 2#)z%K6T  
catch(Exception e){e.printStackTrace ();} ioJ|-@!#o  
#,CK;h9jy!  
"|nh=!L  
} (8Q*NZ  
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public static void main(String[] args) cH6<'W{*  
{ mRT$@xa]J  
new TestMethod(); ^{g('BQx  
} "Ta"5XW  
} iCIU'yI  
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